1. Match List-I (Drive) with List-II (Speed control range) and select the correct answer using the codes given below the lists:
List-I
A. Square wave inverter-fed induction motor
B. PWM inverter-fed induction motor
C. Slip energy recovery scheme with cycloconverter in the rotor circuit
D. Cycloconverter-fed induction motor
List-II
1. 50% of synchronous speed to synchronous speed
2. 10% of base speed to beyond base speed (1: 20)
3. o to 1/3 base speed
4. 67% of synchronous speed to 133% of synchronous speed
5. Zero to 150% of base speed (1: infinity)
Codes:
A B C D
(a) 2 5 4 3
(b) 2 5 3 4
(c) 3 2 4 1
(d) 3 2 1 4
Ans:-C
2. In which one of the following models of transmission lines, is the full charging current assumed to flow over half the length of the line only?
(a) Equivalent-π
(b) Short line
(c) Nominal-?
(d) Nominal-π
Ans:-D
3. If the receiving-end voltage and current are numerically equal to the corresponding sending- end values, that is, Vs = VR and I Is I = I IR I then such a line is called
(a) an infinite line
(b) a natural line
(c) a tuned line
(d) a loss-less line
Ans:-D
4. The convergence characteristic of the Newton- Raphson method for solving a load flow problem is
(a) quadratic
(b) linear
(c) geometric
(d) cubic
Ans:-A
5. If | Vs | = | V R | 66 KV for three-phase transmission and reactance is 11 ohms/phase, then the maximum power transmission per phase would be
(a) 132 MW
(b) 396 MW
(c) 66 MW
(d) None of the above
Ans:-B
6. Consider the following expression:
v—f1(x—rt) + f2 (x + rt)
where f1 and f 2 represent two travelling waves on a transmission l1ne In this case
(a) both waves travel in the positive direction of x
(b) both waves travel in the negative direction of x
(c) wave f 2 travels in the positive direction of x but wave f1 travels in the negative direction of x
(d) wave f1 travels in the positive direction of x but wave f 2 travels in the negative direction of x
Ans:-A
7. For reducing lower footing resistance, it is better to employ
(a) chemical and counterpoise
(b) chemical and ground rods
(c) ground rods and counterpoise
(d) chemical, ground rods and counterpoise
8. A suspension type insulator has three units with self-capacitance C and ground capacitance of 0.2 C having a string efficiency of
(a) 78%
(b) 80%
(c) 82%
(d) 84%
Ans:-C
9. A bundled conductor line compared to a single conductor line (with same conductor cross- sectional area and same mean distance between conductors) has
Self GMD Mutual GMD Per phase Inductance
(a) Lower Nearly same Higher
(b) Higher Lower Nearly same
(c) Higher Nearly same Lower
(d) Lower Higher Higher
Ans:-B
10. In a 14-bus power system network, there are 5 voltage controlled buses. The size of the Jacobian matrix useful for power flow analysis will be:
(a) 16xl6
(c) 21×21
(b) 23×23
(d) 8×8
Ans:-C
11. A thyrite lightning arrester has
(a) inverse resistance characteristics
(b) a gap
(c) efficient earthing
(d) a combination of inverse resistance characteristics and gap
Ans:-D
12. Differential protection of a generator makes use of the principal that, under normal conditions, the current/currents
(a) at the neutral end of a phase winding is zero
(b) in each of the phase windings is identical
(c) at both ends of the phase winding are equal
(d) at the two ends of the phase winding are unequal
Ans:-C
13. The reactance relay is essentially
(a) an over-voltage relay with current restraint
(b) an over-current relay with directional restraint
(c) a directional relay with voltage restraint
(d) a directional relay with current restraint
Ans:-B
14. Severe over-voltages are produced during arcing faults in a power system with the neutral
(a) isolated
(b) solidly earthed
(c) earthed through a low resistance
(d) earthed through an inductive coil
Ans:-D
15. In HVDC transmission system, rectifier firing angle a is kept near
(a) 0°
(b) 15°
(c) 300
(d) 900
Ans:-C
Instructions: The following items consist of two statements, one labelled the ‘Assertion A’and the other labelled the ‘Reason R’. You are to examine these two statements carefully and decide If the Assertion A and the Reason R are individually true and if so, whether the Reason is a correct explanation of the Assertion. Select your answer to these items using the codes given below and mark your answer sheet accordingly.
Codes:
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not a correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
16. Assertion (A): Three-phase transformers of different vector groups should not be operated in parallel.
Reason (R): Transformers belong to different vector groups will not have the same phase sequence on the secondary side.
Ans:-C
17. Assertion (A): In a 3-phase induction motor, the stator is to be wound for 4 poles but by mistake, the rotor is wound for 2 poles only. When the stator is fed from a 50 Hz, 3-phase supply with rotor winding shorted, the motor does not start up. When, however, he wound rotor is replaced by a squirrel-cage rotor, the machine operates without any problem.
Reason (R): Rotor of an induction motor should not have any poles.
Ans:-C
18. In a 3-phase ac machine, the phase emf and output power for a phase spread of 60° are respectively E, and P,; the phase emf and output power for a phase spread of 120° are respectively E2 and P2 In this context which one of the following sets of relations is correct?
(a) E1 = E2 and P1 = P2
(b) E1 = 1.l5 E2 and P1 = 1.15 P2
(c) E1 = l.l5 E2 and P1 = P2
(d) E1 = E2 and P1 = 1.15 P2
Ans:-C
19. The rotor of a three-phase induction machine is replaced by a rotor with a commutator type winding having no external connection between the brushes. The stator is supplied from a balanced three-phase source and the rotor is driven at twice the synchronous speed in the direction opposite to the stator mmf The frequency of the emf induced between consecutive brushes will be (f is the supply frequency)
(a) Zero
(b) F
(c) 2f
(d) 3f
Ans:-C
20. Consider the following statements in connection with the operating characteristics of a dc series motor:
1. It is a constant torque variable speed motors.
2. Its torque is inversely proportional to speed.
3. Its starting torque is high.
4. The power drawn from the supply by the motor remains almost constant at different load torques.
Of these statements:
(a) 1, 3 and 4 are true
(b) l, 2 and 3 are true
(c) 2, 3 and 4 are true
(d) 2 and 4 are true
Ans:-C
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BHEL Free Online practice paper paper Electrical
Electrical Engineering Questions For Engineer Trainee Jobs in BHEL
BHEL aptitude and engineer trainee Electrical sample question paper
Electrical Engineering Questions For Engineer Trainee Jobs in BHEL
BHEL aptitude and engineer trainee Electrical sample question paper
1. The stator of a 415V, 50Hz, 6-pole, 970 rpm, 3- phase slip ring induction motor is fed with normal voltage. The rotor with slip rings open-circuited is rotated at 500 rpm along the normal direction of its rotation. The frequency of the voltage across slip rings will be
(a) 1.5 Hz
(b) 25 Hz
(c) 26.5 Hz
(d) 75 Hz
(a) 1.5 Hz
(b) 25 Hz
(c) 26.5 Hz
(d) 75 Hz
Ans:-B
2. The chart given below indicates four different conditions under which an Induction motor may be called upon to operate, with a constant shaft load.
Applied Rotor
voltage Frequency Resistance
1. Normal Normal Normal
2. 80% Normal Normal
3. 80% 80% Normal
4. Normal Normal 80%
The operating conditions which lead to increasing values of running slips will be In the sequence
(a) 1,4,3,2
(b) 1,4,2,3
(c) 4,1,3,2
(d) 4,1,2,3
Applied Rotor
voltage Frequency Resistance
1. Normal Normal Normal
2. 80% Normal Normal
3. 80% 80% Normal
4. Normal Normal 80%
The operating conditions which lead to increasing values of running slips will be In the sequence
(a) 1,4,3,2
(b) 1,4,2,3
(c) 4,1,3,2
(d) 4,1,2,3
Ans:-C
3. Consider the following statements about the operation of a three-phase induction motor running at full load:
If one of the supply line fuse blows off, the motor will
1. Stall
2. Continue to run with increased slip,
3. continue to run with normal supply current
4. continue to run with excessive supply current
Of these statements
(a) 1 alone is correct
(b) 3 alone is correct
(c) 2 and 3 are correct
(d) 2 and 4 are correct
If one of the supply line fuse blows off, the motor will
1. Stall
2. Continue to run with increased slip,
3. continue to run with normal supply current
4. continue to run with excessive supply current
Of these statements
(a) 1 alone is correct
(b) 3 alone is correct
(c) 2 and 3 are correct
(d) 2 and 4 are correct
Ans:-D
4. A five-limbed core is sometimes used to construct a three-phase power transformer to be connected star/star with isolated neutrals to reduce
(a) Magnetizing current harmonics
(b) Core losses
(c) Leakage reactance
(d) Zero sequence impedance
(a) Magnetizing current harmonics
(b) Core losses
(c) Leakage reactance
(d) Zero sequence impedance
Ans:- A
5. The phenomenon of crawling is usually not formed in slip-ring because these motors have
(a) no space harmonics
(b) high resistance rotor windings
(c) no zig-zag leakage
(d) Comparatively large air-gap
(a) no space harmonics
(b) high resistance rotor windings
(c) no zig-zag leakage
(d) Comparatively large air-gap
Ans:-C
6. Chopper circuits are used to control the speed of dc motors which are fed from fixed dc voltage sources. Variables voltage output can be obtained by which of the following methods?
1. Varying the “on” to “off’ time ratio
2. Adjusting the wave shape
3. Adjusting the frequency of switching
4. Using a saturable reactor in series with the motor
Select the correct answer using the codes given below:
Codes:
(a) l and 2
(b) 1 and 3
(c) 2 and 3
(d) 2 and 4
1. Varying the “on” to “off’ time ratio
2. Adjusting the wave shape
3. Adjusting the frequency of switching
4. Using a saturable reactor in series with the motor
Select the correct answer using the codes given below:
Codes:
(a) l and 2
(b) 1 and 3
(c) 2 and 3
(d) 2 and 4
Ans:-D
7. Match List I with List II and select the correct answer using the codes given below the lists:
List I
A. Rolling mill drive
B. Power drill drive
C. Hoist drive
List II
1. Adjustable speed drive
2. Variable speed drive
3. Constant speed drive
Codes:
A B C
(a) 1 2 3
(b) 2 3 1
(c) 3 1 2
(d) 1 2 1
List I
A. Rolling mill drive
B. Power drill drive
C. Hoist drive
List II
1. Adjustable speed drive
2. Variable speed drive
3. Constant speed drive
Codes:
A B C
(a) 1 2 3
(b) 2 3 1
(c) 3 1 2
(d) 1 2 1
Ans:-C
8. The incremental cost characteristics of the two units in a plant are given by:
IC1 = Rs (0.1P1 + 8.0) per MWh
IC2 Rs (0.15P2 +3.0) per MWh
The optimum sharing of load when the total load is l00 MW is
(a) P1= 6OMW and P2 = 4OMW
(b) P1 = 33.3 MW and P2 = 66.7 MW
(c) P1 40 MW and P2 60 MW
(d) P1 = 66.7 MW and P2 = 33.3 MW
IC1 = Rs (0.1P1 + 8.0) per MWh
IC2 Rs (0.15P2 +3.0) per MWh
The optimum sharing of load when the total load is l00 MW is
(a) P1= 6OMW and P2 = 4OMW
(b) P1 = 33.3 MW and P2 = 66.7 MW
(c) P1 40 MW and P2 60 MW
(d) P1 = 66.7 MW and P2 = 33.3 MW
Ans:-A
9. To increase the visual critical voltage of corona for an overhead line, one solid phase-conductor is replaced by a “bundle” of four smaller conductors per phase, having an aggregate cross-sectional area equal to that of the solid conductor. If the radius of the solid conductor is 40 mm, then the radius of each of the bundle
conductors would be
(a) 10mm
(b) 20 mm
(c) 28.2 mm
(d) 30mm
conductors would be
(a) 10mm
(b) 20 mm
(c) 28.2 mm
(d) 30mm
Ans:-B
10. For an existing ac transmission line, the string efficiency is 80%. If dc voltage is supplied for the same set up, the string efficiency will be
(a) <80%
(b) 80%
(c) 90%
(d) 100%
(a) <80%
(b) 80%
(c) 90%
(d) 100%
Ans:-A
11. In a string of suspension insulators, the voltage distribution across the different units of a string could be made uniform by the use of a grading ring, because it
(a) forms capacitances with link-pins to carry the charging currents from link-pins to earthed structure
(b) forms capacitances which help to cancel the charging current from link-pins
(c) increase the capacitances of lower insulator units to cause equal voltage drop
(d) decrease the capacitances of upper insulator units to cause voltage drop
(a) forms capacitances with link-pins to carry the charging currents from link-pins to earthed structure
(b) forms capacitances which help to cancel the charging current from link-pins
(c) increase the capacitances of lower insulator units to cause equal voltage drop
(d) decrease the capacitances of upper insulator units to cause voltage drop
Ans:-A
12. Match List I with List II and select the correct answer using the codes given below the lists:
List I
(Type of cables)
A. Polyvinyl chloride
B. Paper impregnated
C. Cross-linked polyethylene
List II
(Dielectric constant of insulation)
1. 2.35
2. 3.8
3. 6.0
Codes:
A B C
(a) 1 2 3
(b) 2 3 1
(c) 3 1 2
(d) 3 2 1
List I
(Type of cables)
A. Polyvinyl chloride
B. Paper impregnated
C. Cross-linked polyethylene
List II
(Dielectric constant of insulation)
1. 2.35
2. 3.8
3. 6.0
Codes:
A B C
(a) 1 2 3
(b) 2 3 1
(c) 3 1 2
(d) 3 2 1
Ans:-D
13. A moving coil voltage regulator consists of a laminated magnetic core carrying
(a) Two coils similarly placed on the core and connected in series along with an open- circuited third coil
(b) Two oppositely wound coils and a third short-circuited coil fixed on the core with respect to the first two coils
(c) Two oppositely wound coils arid a third coil short-circuited that can be moved mechanically along the core
(d) Two coils similarly placed on the core connected in series with a third coil open- circuited which moves along the core mechanically
(a) Two coils similarly placed on the core and connected in series along with an open- circuited third coil
(b) Two oppositely wound coils and a third short-circuited coil fixed on the core with respect to the first two coils
(c) Two oppositely wound coils arid a third coil short-circuited that can be moved mechanically along the core
(d) Two coils similarly placed on the core connected in series with a third coil open- circuited which moves along the core mechanically
Ans:-B
14. A generator is connected to an infinite bus through a double circuit transmission. The fault occurring at the middle of one of the transmission lines is subsequently cleared by opening the circuit breakers at both the ends of the line simultaneously. The transient stability limit of the system is improved by
(a) Decreasing the excitation of generator
(b) Decreasing the fault-clearing time
(c) Increasing the fault-clearing time
(d) Increase the transfer reactance between the generator and infinite bus .
(a) Decreasing the excitation of generator
(b) Decreasing the fault-clearing time
(c) Increasing the fault-clearing time
(d) Increase the transfer reactance between the generator and infinite bus .
Ans:-A
15. The velocity of travelling wave through a cable of relative permittivity 9 is
(a) 9 x 108 m /s
(b) 3 x l08 m /s
(c) 108m /s
(d) 2 x 108 m/s
(a) 9 x 108 m /s
(b) 3 x l08 m /s
(c) 108m /s
(d) 2 x 108 m/s
Ans:-D
16. The bus admittance matrix (Y bus) of a power system is not
(a) Symmetric
(b) A square matrix
(c) A full matrix
(d) Generally having dominant diagonal elements
(a) Symmetric
(b) A square matrix
(c) A full matrix
(d) Generally having dominant diagonal elements
Ans:-B
17. A wave-trap is used at the termination of a HVAC overhead line to a station switchyard to
(a) Prevent the transformer magnetising harmonics from reaching the overhead line
(b) Damp the incoming surge waves from the overhead lines
(c) Attenuate sub-harmonic oscillations
(d) Provide for carrier communication
(a) Prevent the transformer magnetising harmonics from reaching the overhead line
(b) Damp the incoming surge waves from the overhead lines
(c) Attenuate sub-harmonic oscillations
(d) Provide for carrier communication
Ans:-C
18. Which of the following are the specific features that apply to a current source inverter?
1. Capacity to feed several motors simultaneously.
2. Capacity to provide straightforward regeneration.
3. Inherent protection in case there is a load short-circuits.
Select the correct answer using the codes given below:
Codes:
(a) 1, 2 and 3
(b) 1 and 2
(c) 1 and 3
(d) 2 and 3
18. Which of the following are the specific features that apply to a current source inverter?
1. Capacity to feed several motors simultaneously.
2. Capacity to provide straightforward regeneration.
3. Inherent protection in case there is a load short-circuits.
Select the correct answer using the codes given below:
Codes:
(a) 1, 2 and 3
(b) 1 and 2
(c) 1 and 3
(d) 2 and 3
Ans:-C
19. Consider the following statements:
A free wheeling diode across the load circuit of a two-pulse converter
1. Improves the operating power factor.
2. Makes the distortion factor (I1 / I)vary as a function of firing angle
3. is effective in reducing the smoothing inductance.
4. Distorts the line current
Of these statements:
(a) 1, 3 and 4 are correct
(b) 1, 2 and 3 are correct
(c) 1, 2 and 4 are correct
(d) 2, 3 and 4 are correct
A free wheeling diode across the load circuit of a two-pulse converter
1. Improves the operating power factor.
2. Makes the distortion factor (I1 / I)vary as a function of firing angle
3. is effective in reducing the smoothing inductance.
4. Distorts the line current
Of these statements:
(a) 1, 3 and 4 are correct
(b) 1, 2 and 3 are correct
(c) 1, 2 and 4 are correct
(d) 2, 3 and 4 are correct
Ans:-C
Directions: The following items consist of two statements, one labelled the ‘Assertion A’ and the other labelled the ‘Reason R’. You are to examine these two statements carefully and decide f the Assertion A and the Reason R are individually true and f so, whether the Reason is a correct explanation of the Assertion. Select your answer to these items using the codes given below and mark your answer sheet accordingly.
Codes:
(a) Both A and R is true and R is the correct explanation of A
(b) Both A and R is true but R is not a correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Codes:
(a) Both A and R is true and R is the correct explanation of A
(b) Both A and R is true but R is not a correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
20. Assertion (A): The poles of the driving-point immitance function of an RLC network have negative real parts.
Reason (R): The network is made up of passive elements.
Reason (R): The network is made up of passive elements.
Ans:-C
21. Assertion (A): A vector A = 2y ix — x i y represent a magnetic field.
Reason(R): V.A = 0
Reason(R): V.A = 0
Ans:-B
22. Assertion (A): The steady-state error of a type 1 system due to acceleration input is zero. Reason (R): Type 1 system has a zero positional error constant.
Ans:-C
23. Assertion (A): Phase-lead compensation is generally less effective if the uncompensated system is highly unstable.
Reason (R): Phase-lead compensator adds a zero to the right of the pole of closed-loop system.
Reason (R): Phase-lead compensator adds a zero to the right of the pole of closed-loop system.
Ans:-B
24. Assertion (A): A permanent magnet moving coil instrument does not work satisfactorily when the frequency of the signal is high.
Reason (R): The power loss in the moving coil becomes excessive at high frequency.
Reason (R): The power loss in the moving coil becomes excessive at high frequency.
Ans:-A
25. Assertion (A): In order obtain voltage gain and current gain independent of the transistor parameters, voltage shunt negative feedback can be used in CE amplifier.
Reason (R): Due to negative feedback, the input impedance increase and output impedance reduces.
Reason (R): Due to negative feedback, the input impedance increase and output impedance reduces.
Ans:-A
26. Assertion (A): the iron losses of a transformer increase if the supply frequency is increased with applied voltage remaining constant.
Reason (R): The flux density in a core is inversely proportional to the frequency of the exciting current.
Reason (R): The flux density in a core is inversely proportional to the frequency of the exciting current.
Ans:-C
27. Assertion (A): the presence of damper winding in the alternator increases the initial value of short circuit current when a fault occurs.
Reason (R): The damper winding is closely coupled to the field winding and hence does not allow the field flux linkages to decay.
Reason (R): The damper winding is closely coupled to the field winding and hence does not allow the field flux linkages to decay.
Ans:-B
28. Assertion (A): It is necessary to provide reactive power compensating equipment to generate or absorb reactive volt amps to maintain a voltage profile on transmission system within limits.
Reason (R): A synchronous compensator delivers both leading reactive and lagging reactive VARS depending on the excitation.
Reason (R): A synchronous compensator delivers both leading reactive and lagging reactive VARS depending on the excitation.
Ans:-C
29. Assertion (A): An over-excited synchronous motor draws a leading current from the mains. Reason (R): A synchronous machine irrespective of its operation as generator or motor has demagnetising armature reaction when overexcited.
Ans:-D
30. Assertion (A): There is no control on tie-line power flow when flat frequency control method is used for controlling the frequency of an interconnected power system.
Reason (R): The job of maintaining frequency
Reason (R): The job of maintaining frequency
Ans:-B
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Model Paper Junior Engineers (Electrical) RRB
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Solved question paper for Junior engineer(electrical)
1. The frequency of DC current
(a) Equal to voltage magnitude
(b) 0
(c) Double of AC frequency
(d) 50 HZ
Ans : b
download SSC Junior Engineers Sample paper
Solved question paper for Junior engineer(electrical)
1. The frequency of DC current
(a) Equal to voltage magnitude
(b) 0
(c) Double of AC frequency
(d) 50 HZ
Ans : b
2. The current flowing in a purely inductive circuit of 30 mH on application of 230 V,
50 Hz single phase supply is 24.4 A. If the frequency of the applied voltage is
increased to 100 Hz the current flowing in the same circuit will be
(a) 24.4 A
(b) 48.8 A
(c) 12.2 A
(d) 6.1 A
Ans : c
50 Hz single phase supply is 24.4 A. If the frequency of the applied voltage is
increased to 100 Hz the current flowing in the same circuit will be
(a) 24.4 A
(b) 48.8 A
(c) 12.2 A
(d) 6.1 A
Ans : c
3. Find the total resistance when two 3 Ohm resistances are connected in parallel.
(a) 1.11 ohms
(b) 1.5 ohms
(c) 0.707 ohms
(d) 1.23 ohms
Ans : b
4. Voltage drop in a resistance given by
(a) mmf/reluctance
(b) IR
(c) I/R
(d) VI
Ans : b
(a) 1.11 ohms
(b) 1.5 ohms
(c) 0.707 ohms
(d) 1.23 ohms
Ans : b
4. Voltage drop in a resistance given by
(a) mmf/reluctance
(b) IR
(c) I/R
(d) VI
Ans : b
5. Off-line converter, SMPS has
a. AC input and dc output
b .DC input and dc output
c. AC input and ac output
d. None
Ans. a
6. Filter circuits are constructed by means of
a. Diode
b. Resistors
c. Transformers
d. Capacitor and inductors
a. AC input and dc output
b .DC input and dc output
c. AC input and ac output
d. None
Ans. a
6. Filter circuits are constructed by means of
a. Diode
b. Resistors
c. Transformers
d. Capacitor and inductors
Ans. d
7. Resistance of the diode is decreased when
a. Forward biased
b. Reverse biased
c. Both forward and reverse biased
d. Either a or b
a. Forward biased
b. Reverse biased
c. Both forward and reverse biased
d. Either a or b
Ans. a
8. In earlier time is used for voltage regulation.
a. Diode
b. Transistors
c. Vacuum tubes and glow bulbs
d. SMPS
a. Diode
b. Transistors
c. Vacuum tubes and glow bulbs
d. SMPS
Ans. c
9. is the equipment used during power failure.
a. Rectifier
b. Voltage regulators
c. UPS
d. SMPS
a. Rectifier
b. Voltage regulators
c. UPS
d. SMPS
Ans. c
10. Peak factor of the sine wave is equal to
(a) 0.901
(b) 1.414
(c) 1.1
(d) 1.11
Ans :b
(a) 0.901
(b) 1.414
(c) 1.1
(d) 1.11
Ans :b
11. The amplitude of current of full wave rectified sinusoidal wave is 80 A, its average
value will be
(a) 25.44A
(b) 80A
(c) 40A
(d) 56.56A
Ans : a
12.Find the total current supplied to the lamp rated 100w .when supply voltage is 200 v.
(a) 1.75A
(b) 2A
(c) 0.5A
(d) 1A
(e) Ans : c
13. The power factor of a inductive circuit is
(a) Lagging
(b) Leading
(c) Zero lagging
(d) Unity
Ans : a
14. The power factor of a purely capacitive circuit is always
(a) Lagging
(b) Leading
(c) Unity
(d) Zero lagging
Ans : b
value will be
(a) 25.44A
(b) 80A
(c) 40A
(d) 56.56A
Ans : a
12.Find the total current supplied to the lamp rated 100w .when supply voltage is 200 v.
(a) 1.75A
(b) 2A
(c) 0.5A
(d) 1A
(e) Ans : c
13. The power factor of a inductive circuit is
(a) Lagging
(b) Leading
(c) Zero lagging
(d) Unity
Ans : a
14. The power factor of a purely capacitive circuit is always
(a) Lagging
(b) Leading
(c) Unity
(d) Zero lagging
Ans : b
15. The overall circuit power factor of a RLC series circuit is found to be 0.898 lagging. The nature of the resultant circuit is
(a) Resistive
(b) Inductive
(c) Capacitive
(d) None of these
Ans : b
(a) Resistive
(b) Inductive
(c) Capacitive
(d) None of these
Ans : b
16. The maximum, rms and average value of a periodic current wave form is 100 A,
64.42A and 57.5A, respectively. The peak factor of this wave is
(a) 0.644
(b) 1.552
(c) 1.12
(d) None of these
Ans : b
17. In a parallel resistance circuit
(a) Power is same in all resistance
(b) Current is same in all resistance
(c) Voltage is same in all resistance
(d) Resistances are same
Ans : c
64.42A and 57.5A, respectively. The peak factor of this wave is
(a) 0.644
(b) 1.552
(c) 1.12
(d) None of these
Ans : b
17. In a parallel resistance circuit
(a) Power is same in all resistance
(b) Current is same in all resistance
(c) Voltage is same in all resistance
(d) Resistances are same
Ans : c
18. Find the total resistance when 2 Ohm and 4 Ohm resistances are in parallel.
(a) 1.33 Ohms
(b) 0.33 Ohms
(c) 2.33 Ohms
(d) 1 Ohm
Ans : a
(a) 1.33 Ohms
(b) 0.33 Ohms
(c) 2.33 Ohms
(d) 1 Ohm
Ans : a
19. Expression for mmf in terms of field strength is
(a) HI
(b) H/I
(c) HL
(d) H/L
Ans : c
20. is the property of magnetic which opposes the flow of flux through it.
(a) Resistance
(b) MMF
(c) Reluctance
(d) emf
Ans : c
21. is the property of electrical conductor which oppose the flow of current through it
(a) Reluctance
(b) emf
(c) mmf
(d) Resistance
Ans : d
22. Reluctance is expressed in
(a) Ampere Weber
(b) Ohm
(c) Ampere/Weber
(d) Volt/Ampere
Ans : c
(a) HI
(b) H/I
(c) HL
(d) H/L
Ans : c
20. is the property of magnetic which opposes the flow of flux through it.
(a) Resistance
(b) MMF
(c) Reluctance
(d) emf
Ans : c
21. is the property of electrical conductor which oppose the flow of current through it
(a) Reluctance
(b) emf
(c) mmf
(d) Resistance
Ans : d
22. Reluctance is expressed in
(a) Ampere Weber
(b) Ohm
(c) Ampere/Weber
(d) Volt/Ampere
Ans : c
23. Reciprocal of reluctance is termed as
(a) Conductance
(b) Permenance
(c) Permeability
(d) None of these
Ans : b
24. Ohm’s law for electric circuit will be
(a) emf= current/resistance
(b) emf= current X resistance
(c) emf= resistance/current
(d) emf= 1/( resistance X current)
Ans : b
(a) Conductance
(b) Permenance
(c) Permeability
(d) None of these
Ans : b
24. Ohm’s law for electric circuit will be
(a) emf= current/resistance
(b) emf= current X resistance
(c) emf= resistance/current
(d) emf= 1/( resistance X current)
Ans : b
25. Ohm’s law for magnetic circuit will be
(a) mmf= flux /resistance
(b) flux= mmf X resistance
(c) reluctance = mmf/ flux
(d) Resistance= mmf X flux
Ans : c
(a) mmf= flux /resistance
(b) flux= mmf X resistance
(c) reluctance = mmf/ flux
(d) Resistance= mmf X flux
Ans : c
.....................................................----------------------------------................................................................
Free Online Quiz For Assistant Engineer in Doordarshan and AIR 2010
Free online objective Quiz containing Questions on
electrostatic ,Wires carrying charge,induced field and potential.Intensity of charged particles ,induced field in circular coil ,
electromagnet and electromagnetic field ,dipole moment
Free online objective Quiz containing Questions on
electrostatic ,Wires carrying charge,induced field and potential.Intensity of charged particles ,induced field in circular coil ,
electromagnet and electromagnetic field ,dipole moment
Units like coulomb,unit of force,gauss,potential energy,electrostatics
Physics knowledge quizz free
Physics knowledge quizz free
1. A particle is moving uniformly with an angular velocity ω on the circumference of a circle of radius r. The linear velocity will be given by
(a) rω
(c) r/ω
(b)2Πrω
(d) ω/r
(a) rω
(c) r/ω
(b)2Πrω
(d) ω/r
Ans:a
2. Line spectrum is obtained from the?
(a) Sun
(b) Filament of the bulb
(c) Mercury lamp
(d) Burning coal
(a) Sun
(b) Filament of the bulb
(c) Mercury lamp
(d) Burning coal
Ans:c
3. A moving charge produces:
(a) neither electric field nor magnetic field
(b) electro-static field only
(c) magnetic field only
(d) both magnetic and electro-static fields
(a) neither electric field nor magnetic field
(b) electro-static field only
(c) magnetic field only
(d) both magnetic and electro-static fields
Ans:c
4. α, β and γrays emitted from a radioactive source are passed through a 0.5 cm. thick aluminum sheet. The out going radiations will consist of:
(a) α, β and γray
(b) β and γray
(c) γray
(d) αrays
Ans:b
(a) α, β and γray
(b) β and γray
(c) γray
(d) αrays
Ans:b
5. Light year is a unit of
(a) time
(b) distance
(c) velocity
(d) acceleration
(a) time
(b) distance
(c) velocity
(d) acceleration
Ans:b
6. It is easier to draw up wooden block along an inclined plane than bang it up vertically principally because:
(a) the friction is reduced
(b) only a part of the weight has to be overcome
(c) the mass becomes smaller
(d) g becomes smaller
Ans:b
6. It is easier to draw up wooden block along an inclined plane than bang it up vertically principally because:
(a) the friction is reduced
(b) only a part of the weight has to be overcome
(c) the mass becomes smaller
(d) g becomes smaller
Ans:b
7. If a piece of ice floating on the surface of water in a beaker melts completely, the level of water
(a) rises
(b) remains the same
(c) falls
(d) initially rises and then falls
Ans:b
(a) rises
(b) remains the same
(c) falls
(d) initially rises and then falls
Ans:b
8. A Kelvin thermometer and a Fahrenheit thermometer used to record temperature of melting metal, read the same. What will a celcius thermometer read at that temperature?
(a) 301.25°
(b) 273°
(c) 457°
(d) 760°
Ans:a
(a) 301.25°
(b) 273°
(c) 457°
(d) 760°
Ans:a
9. A hydrogen-filled balloon expands as it rises and may even burst after rising very high in the atmosphere. This happens because:
(a) the temperature increases with height
(b) the temperature decreases with height
(c) the atmospheric pressure increases with height
(d) the atmospheric pressure decreases with height
(a) the temperature increases with height
(b) the temperature decreases with height
(c) the atmospheric pressure increases with height
(d) the atmospheric pressure decreases with height
Ans:d
10. if two substances of equal volumes but of different densities are dropped from the same height simultaneously, then
(a) the body of lower density will reach the earth earlier
(b) both the bodies will reach the earth simultaneously
(c) The body of higher density will reach earlier
(d) It depends upon the place
Ans:b
(a) the body of lower density will reach the earth earlier
(b) both the bodies will reach the earth simultaneously
(c) The body of higher density will reach earlier
(d) It depends upon the place
Ans:b
11. When the bob of a pendulum is at the mean position (minimum displacement) of its motion, its total energy is:
(a) all potential
(b) zero
(c) all kinetic
(d) partly kinetic partly potential
Ans:c
(a) all potential
(b) zero
(c) all kinetic
(d) partly kinetic partly potential
Ans:c
12. A red and a green pencil are taken in a room illuminated with green light. In the room:
(a) both pencils will appear dark
(b) pencils will appear as red and green respectively
(c) red pencil.will appear dark and green pencil as green
(d) red pencil will appear red and green pencil dark
(a) both pencils will appear dark
(b) pencils will appear as red and green respectively
(c) red pencil.will appear dark and green pencil as green
(d) red pencil will appear red and green pencil dark
Ans:c
13. The consumption of electrical energy in the household is measured in terms of:
(a) Kilowatt hour
(b) Kilowatts
(c) Joules
(d) Kilo Joules
13. The consumption of electrical energy in the household is measured in terms of:
(a) Kilowatt hour
(b) Kilowatts
(c) Joules
(d) Kilo Joules
Ans:a
14. A magnet is placed in earth’s magnetic field with north pole of the magnet pointing north. At the neutral point:
(a) the earth’s magnetic field is zero
(b) the magnet’s magnetic field is zero
(c) the fields of the magnet and the earth are equal and in the same direction
(d) the fields of the magnet and the earth are equal and opposite
(a) the earth’s magnetic field is zero
(b) the magnet’s magnetic field is zero
(c) the fields of the magnet and the earth are equal and in the same direction
(d) the fields of the magnet and the earth are equal and opposite
Ans:d
15. Sudden fall of a barometer reading indicates:
(a) storm
(b) dry weather
(c) fine weather
(d) cold weather
(a) storm
(b) dry weather
(c) fine weather
(d) cold weather
Ans:a
16. If a ball and a rectangular block of different metal when completely immersed in a liquid, have the same loss of weight, then
(a) ball and rectangular block have same density
(b) ball and rectangular block have Weight in air
(c) ball and rectangular block have same volume
(d) ball and rectangular block have immersed to the same depth
(a) ball and rectangular block have same density
(b) ball and rectangular block have Weight in air
(c) ball and rectangular block have same volume
(d) ball and rectangular block have immersed to the same depth
Ans:c
17. If the period of oscillation of a simple pendulum is 4 seconds and we want to convert it into a second pendulum, then we have to:
(a) make the length of the pendulum one fourth of the previous length
(b) double the length of the pendulum
(c) make the length of the pendulum half of the previous length
(d) double the mass of the bob
(a) make the length of the pendulum one fourth of the previous length
(b) double the length of the pendulum
(c) make the length of the pendulum half of the previous length
(d) double the mass of the bob
Ans:a
18. The escape velocity of a body from the earth depends upon:
(a) mass of the body
(b) radius of the earth as well as the value of g
(c) the radius of the earth only
(d) volume of the body
(a) mass of the body
(b) radius of the earth as well as the value of g
(c) the radius of the earth only
(d) volume of the body
Ans:b
19. A cyclist taking a turn bends inside because:
(a) he feels pleasure in doing so
(b) he increases speed in doing so
(c) he obtains necessary Centripetal force
(d) he avoids accidents
Ans:c
(a) he feels pleasure in doing so
(b) he increases speed in doing so
(c) he obtains necessary Centripetal force
(d) he avoids accidents
Ans:c
20. If the surface of water in a lake is just going to freeze, then the temperature of water at the bottom is
(a) 0°C
(b) 4°C
(c) 3°C
(d) none of these
Ans:b
(a) 0°C
(b) 4°C
(c) 3°C
(d) none of these
Ans:b
21. The tangent law is applicable only when:
(a) there are at least two magnetic fields
(b) there two uniform magnetic fields mutually perpendicular to each other
(c) one strong magnetic field and the other weak magnetic field
(d) in the present magnetic fields one should be horizontal component of the earth’s magnetic field
Ans:b
(a) there are at least two magnetic fields
(b) there two uniform magnetic fields mutually perpendicular to each other
(c) one strong magnetic field and the other weak magnetic field
(d) in the present magnetic fields one should be horizontal component of the earth’s magnetic field
Ans:b
22. A moving coil galvanometer is converted into an ammeter by putting:
(a) a high resistance in parallel
(b) a low resistance in series
(c) a low resistance in parallel
(d) a high resistance in series
Ans:c
(a) a high resistance in parallel
(b) a low resistance in series
(c) a low resistance in parallel
(d) a high resistance in series
Ans:c
23. Lenz’s law is derived from the law of conservation of:
(a)momentum
(b) energy
(c)charge
(d) magnetism
Ans:b
(a)momentum
(b) energy
(c)charge
(d) magnetism
Ans:b
24. On which one of the factors does the sensivity of a galvanometer depend?
(a) number of the turns of the coil
(b) the temperature of the room
(c) the current flowing in it
(d) the potential difference between the two ends.
Ans:a
(a) number of the turns of the coil
(b) the temperature of the room
(c) the current flowing in it
(d) the potential difference between the two ends.
Ans:a
25. The wavelength of X-rays is of the order of:
(a) 0.1 cm
(b) 10 2cm
(c)10 -4cm
(d)10 10 -8cm
Ans:d
(a) 0.1 cm
(b) 10 2cm
(c)10 -4cm
(d)10 10 -8cm
Ans:d
26. Lamps used for street lighting are connected in
(a) parallel
(b) series and parallel both
(c) series
(d) none of the above
Ans:a
(a) parallel
(b) series and parallel both
(c) series
(d) none of the above
Ans:a
27. A. C. can be measured with the help of:
(a) moving coil galvanometer
(b) hot wire ammeter
(c) tangent galvanometer
(d) galvanometer
(a) moving coil galvanometer
(b) hot wire ammeter
(c) tangent galvanometer
(d) galvanometer
Ans:b
...............................................--------------------------------..........................................................
Sample test paper EA Engineering Assistants in AIR and DD 2010
Containing physics MCQ Questions on
electrical field
magnetic wires
magnetic field intensity
electrical coil
electrical charges
magnetic
magnetic induction
induction magnetic
electrical magnetic
magnetic plates
Containing physics MCQ Questions on
electrical field
magnetic wires
magnetic field intensity
electrical coil
electrical charges
magnetic
magnetic induction
induction magnetic
electrical magnetic
magnetic plates
1. Which one of the following physical quantities, is not defined in the terms of force per unit area:
(a) pressure
(b) strain
(c) stress
(d) Young’s modulus
(a) pressure
(b) strain
(c) stress
(d) Young’s modulus
Ans:b
2. The distance moved by a moving body is equal to:
(a) area between the distance-time graph and distance axis
(b) area between the speed-time graph and time axis
(c) area between the distance-time graph and time axis
(d) area between the speed-time graph and distance axis.
Ans:b
(a) area between the distance-time graph and distance axis
(b) area between the speed-time graph and time axis
(c) area between the distance-time graph and time axis
(d) area between the speed-time graph and distance axis.
Ans:b
3. A beaker containing water weighs 100 gm. It is placed on the pan of a balance and a piece of metal weighing 70 gm. and having a volume of 10cc. is placed inside the water in the beaker. The weight of the beaker and the metal would be :
(a) 170gm.
(c) 100gm.
(b)160gm.
(d)30gm.
Ans:a
(a) 170gm.
(c) 100gm.
(b)160gm.
(d)30gm.
Ans:a
4. For the same kinetic energy, the momentum shall be maximum for:
(a) electron
(b) proton
(c) deuteron
(d) alpha particle
Ans:d
(a) electron
(b) proton
(c) deuteron
(d) alpha particle
Ans:d
5. The common balance works on the principle of equality of:
(a) forces
(b) moments of forces
(c) masses
(d) masses of pans
Ans:b
(a) forces
(b) moments of forces
(c) masses
(d) masses of pans
Ans:b
6. A particle moves in a circle of radius R with a constant speed under a centripetal force F. The work done in completing a full circle is:
(a) 2RF
(b) ΠR2F
(c) 2ΠRF
(d)Zero
(b) ΠR2F
(c) 2ΠRF
(d)Zero
Ans:d
7. When two quantities are plotted on the graph paper against each other and the result so obtained is a st. line, then
(a) Both the quantities are equal
(b) The quantities are inversely proportional to each other
(c) Sum of both is zero
(d) The quantities are proportional to each other
Ans:d
8. What is the order of magnitude of 260°?
(a)103
(b) 104
(c)102
(d) 10
Ans:c
9. The maximum value of g is:
(a) At the poles
(b) At the top of the Mount Everest
(c) At the equator
(d) Below the sea level
Ans:a
7. When two quantities are plotted on the graph paper against each other and the result so obtained is a st. line, then
(a) Both the quantities are equal
(b) The quantities are inversely proportional to each other
(c) Sum of both is zero
(d) The quantities are proportional to each other
Ans:d
8. What is the order of magnitude of 260°?
(a)103
(b) 104
(c)102
(d) 10
Ans:c
9. The maximum value of g is:
(a) At the poles
(b) At the top of the Mount Everest
(c) At the equator
(d) Below the sea level
Ans:a
10. A fixed volume of gas at 27°C exerts a pressure of 750 mm. If the gas is heated to a pressure of 1500mm., temperature must be:
(a) 600°C
(b) 327°C
(c) 54°C
(d) 13.5°C
Ans:b
(a) 600°C
(b) 327°C
(c) 54°C
(d) 13.5°C
Ans:b
11. A body of mass 2 kg acted upon by a constant force, travels a distance of 3 metres in the first second and a further distance of meter in the next second. The force acting on the body is?
(a) 12 Newtons
(b) 8 Newtons
(c) 4 Newtons
(d) 1 Newton
(a) 12 Newtons
(b) 8 Newtons
(c) 4 Newtons
(d) 1 Newton
Ans:c
12. Two forces each equal to P acting at a point have no resultant. The angle between the two forces must be equal to:
(a)180°
(b) 90°
(c)0°
(d) 120°
(a)180°
(b) 90°
(c)0°
(d) 120°
Ans:a
13. A jet engine works on the principle of:
(a) conservation of energy
(b) conservation of momentum
(c) conservation of mass
(d) conservation of temperature
(a) conservation of energy
(b) conservation of momentum
(c) conservation of mass
(d) conservation of temperature
Ans:b
14. A sharp knife cuts much better than a blunt one because?
(a) Area of sharp knife is much less than the area of the blunt one
(b) sharp knife is brighter
(c) sharp knife is colder
(d) sharp knife is costly
Ans:a
(a) Area of sharp knife is much less than the area of the blunt one
(b) sharp knife is brighter
(c) sharp knife is colder
(d) sharp knife is costly
Ans:a
15. A man carries a heavy box on his head on a horizontal plane from one place to another.
In this he does?
(a) maximum work
(b) no work
(c) negative work
(d) minimum work
Ans:b
In this he does?
(a) maximum work
(b) no work
(c) negative work
(d) minimum work
Ans:b
16. The bob of a second’s pendulum is replaced by another bob of double mass. The new time period will be:
(a) 4 sec.
(c) 2 sec.
(b) 1 sec
(d) 3 sec.
(a) 4 sec.
(c) 2 sec.
(b) 1 sec
(d) 3 sec.
Ans:c
17.A device for measuring temperatures at a distance is
(a) gas thermometer
(b) mercury thermometer
(c) radiation
(d) maximum-minimum thermometer
(a) gas thermometer
(b) mercury thermometer
(c) radiation
(d) maximum-minimum thermometer
Ans:c
18. A piece of ice is floating in a concentrated solution of common salt (in water) in a pot. When ice melts completely, the level of solution will:
(a) go up
(b) remain the same
(c) go down
(d) first go up then go down
(a) go up
(b) remain the same
(c) go down
(d) first go up then go down
Ans:a
19. A radioactive source has a half-life of 30 days. During a period of 90 days the fraction of atoms that have decayed would be
(a)100%
(b) 87.5%
(c)64%
(d) 50%
(a)100%
(b) 87.5%
(c)64%
(d) 50%
Ans:b
20. A black body emits:
(a) radiations of all wavelengths
(b) no radiations
(c) radiations of only one wavelength
(d) radiations of selected wavelengths
(a) radiations of all wavelengths
(b) no radiations
(c) radiations of only one wavelength
(d) radiations of selected wavelengths
Ans:a
21. A near sighted person cannot see distinctly beyond 50 cm. from his eye. The power in diopter of spectacle lenses which will enable him to see distant objects clearly is
(a) +50
(b) —50
(c) +2
(d) —2
Ans:c
(a) +50
(b) —50
(c) +2
(d) —2
Ans:c
22. Size of a nucleus is of the order of?
(a)10-18m
(b) 10-14m
(c)10-10m
(d) 10-6m
Ans:b
(a)10-18m
(b) 10-14m
(c)10-10m
(d) 10-6m
Ans:b
23. The freezing point on a thermometer is marked as 20° and the boiling point as 150°C. A temperature of 60°C on this thermometer will be read as:
(a)40°
(b) 65°
(c)98°
(d) 110°
Ans:c
(a)40°
(b) 65°
(c)98°
(d) 110°
Ans:c
24. In isothermal expansion of an ideal gas:
(a) heat content remains constant
(b) temperature remains constant
(c) both heat content and temperature remain constant
(d) pressure and temperature of the gas remain constant
Ans:b
(a) heat content remains constant
(b) temperature remains constant
(c) both heat content and temperature remain constant
(d) pressure and temperature of the gas remain constant
Ans:b
25. A man standing between two cliffs hears the first echo of a sound after 2 sec. and the second echo 3 sec. after the initial sound. If the speed of sound be 330 m/sec. the distance between the two cliffs should be
(a)1650 m.
(b)990 m.
(c)825 m
(d) 660 m.
Ans:c
(a)1650 m.
(b)990 m.
(c)825 m
(d) 660 m.
Ans:c
26. In a resonance tube experiment the first resonance is obtained for 10 cm. of air column and the second for 32 cm. The end correction for this apparatus is equal to?
(a)0.5 cm
(b)1.0 cm
(c)1.5 cm
(d) 2 cm
Ans:b
(a)0.5 cm
(b)1.0 cm
(c)1.5 cm
(d) 2 cm
Ans:b
27. The ratio of the specific heat of air at constant pressure to its specific heat at constant volume is?
(a) zero
(b) greater than one
(c) less than one
(d) equal to one
(a) zero
(b) greater than one
(c) less than one
(d) equal to one
Ans:b
28. A convex lens has a focal length of 10 cm. When it is immersed in water it will behave
as?
(a) a convex tens of 10 cm. focal length
(b) a concave lens of 10 cm. focal length
(c) a convex lens of focal length greater than 10cm.
(d) a convex lens of focal length less than 10 cm.
Ans:c
29. Two particles having charges q1 and q2 when kept at a certain distance exert a force F on each other. If the distance between the two particles is reduced to half and the charge on each particle is doubled the force between the particles would be ?
(a)2F
(b)4F
(c)8F
(d)16F
Ans:d
as?
(a) a convex tens of 10 cm. focal length
(b) a concave lens of 10 cm. focal length
(c) a convex lens of focal length greater than 10cm.
(d) a convex lens of focal length less than 10 cm.
Ans:c
29. Two particles having charges q1 and q2 when kept at a certain distance exert a force F on each other. If the distance between the two particles is reduced to half and the charge on each particle is doubled the force between the particles would be ?
(a)2F
(b)4F
(c)8F
(d)16F
Ans:d
30. A small magnet is placed perpendicular to a constant magnetic field. The forces acting on the magnet will result in?
(a) rotation
(b) translation
(c) no motion at all
(d) rotation as well as translation
Ans:a
(a) rotation
(b) translation
(c) no motion at all
(d) rotation as well as translation
Ans:a
31. A hollow metallic sphere is charged. Inside the sphere?
(a) the potential is zero but the electric field is finite
(b) the electric field is zero but the potential is finite
(c) both the electric field and the potential are finite
(d) both the electric field and the potential are zero
Ans:b
(a) the potential is zero but the electric field is finite
(b) the electric field is zero but the potential is finite
(c) both the electric field and the potential are finite
(d) both the electric field and the potential are zero
Ans:b
32. Two electric lamps each of 100 watts 220 V are connected in series to a supply of 220 volts. The power consumed would be:
(a)100 Watts
(b) 200 Watts
(c)25 Watts
(d) 50 Watts
Ans:d
(a)100 Watts
(b) 200 Watts
(c)25 Watts
(d) 50 Watts
Ans:d
33. A transformer is:
(a) a device for stepping up D.C.
(b) a generator of current
(c) device for converting direct current into alternating current
(d) a device for stepping up or down the voltage of A.C. supply
Ans:d
(a) a device for stepping up D.C.
(b) a generator of current
(c) device for converting direct current into alternating current
(d) a device for stepping up or down the voltage of A.C. supply
Ans:d
34. Transistor act as a?
(a) conductor
(b) semi-conductor
(c) insulator
(d) thermionic valve
(a) conductor
(b) semi-conductor
(c) insulator
(d) thermionic valve
Ans:d
35. The sky is blue because:
(a) there is more blue light in the sunlight
(b) of scattering of sunlight by air molecules in the atmosphere
(c) of scattering of sunlight by dust particles in the atmosphere
(d) other colours are absorbed by heavenly bodies
Ans:b
(a) there is more blue light in the sunlight
(b) of scattering of sunlight by air molecules in the atmosphere
(c) of scattering of sunlight by dust particles in the atmosphere
(d) other colours are absorbed by heavenly bodies
Ans:b
36. A cyclonic storm is indicated by a change in the atmospheric pressure. In atmospheric
pressure there is a:
(a)sudden rise
(b) gradual rise
(c)sudden fall
(d) gradual fall
Ans:c
pressure there is a:
(a)sudden rise
(b) gradual rise
(c)sudden fall
(d) gradual fall
Ans:c
37. The electric field inside a hollow conducting sphere will ?
(a) increases towards the centre
(b) decreases towards the centre
(c) is finite and constant throughout
(d) is zero
Ans:d
(a) increases towards the centre
(b) decreases towards the centre
(c) is finite and constant throughout
(d) is zero
Ans:d
38. Imperfect gases are those:
(a) which contain impurities
(b) which do not obey Charle’s and Boyle’s laws
(c) whose molecules are not spherical
(d) whose molecules cannot be regarded as point masses
Ans:b
(a) which contain impurities
(b) which do not obey Charle’s and Boyle’s laws
(c) whose molecules are not spherical
(d) whose molecules cannot be regarded as point masses
Ans:b
39. Sonar is a device for:
(a) location and ranging of aircraft’s
(b) location and ranging submarines
(c) producing a musical note of high quality
(d) measuring frequency of musical notes
Ans:b
(a) location and ranging of aircraft’s
(b) location and ranging submarines
(c) producing a musical note of high quality
(d) measuring frequency of musical notes
Ans:b
40. Cyclotron is a device to produce:
(a) atomic energy
(b) high energy electrons
(c) high energy photons
(d) high energy protons
Ans:d
(a) atomic energy
(b) high energy electrons
(c) high energy photons
(d) high energy protons
Ans:d
41. Which one of the following is not a vector?
(a) Velocity
(b) Acceleration
(c) Force
(d) Energy
Ans:d
(a) Velocity
(b) Acceleration
(c) Force
(d) Energy
Ans:d
42. Two steel balls of mass 1 kg. and 2kg. and a lead ball of 10kg. are released together from the top of tower 30 metres high. Assuming the path to be in vacuum
(a) the lead ball reaches the ground earlier
(b) the 1 kg. steel bail reaches the ground earlier
(c) all the balls reach the ground simultaneously
(d) the 2 kg. steel ball reaches the ground earlier
Ans:c
(a) the lead ball reaches the ground earlier
(b) the 1 kg. steel bail reaches the ground earlier
(c) all the balls reach the ground simultaneously
(d) the 2 kg. steel ball reaches the ground earlier
Ans:c
43. After a watch has been wound, it?
(a) has great energy stored in it
(b) possesses mechanical potential energy stored in it
(c) has eletrical energy stored in it
(d) has no energy in it
Ans:b
(a) has great energy stored in it
(b) possesses mechanical potential energy stored in it
(c) has eletrical energy stored in it
(d) has no energy in it
Ans:b
44. Two plane mirrors are set at right angles and a flower is placed in any position in between the mirrors. The number of images of the flower which will be seen is?
(b) two
(d) four
(a) one
(c) three
Ans:c
(b) two
(d) four
(a) one
(c) three
Ans:c
45. In which of the following cases total internal reflection cannot be obtained?
(a) ray going from water to glass
(b) a ray going from glass to water
(c) a ray going from glass to air
(d) a ray going from water to air.
Ans:a
(a) ray going from water to glass
(b) a ray going from glass to water
(c) a ray going from glass to air
(d) a ray going from water to air.
Ans:a
46. When white light passes through a glass prism, we get a spectrum on the other side of the prism. In the emergent beam the ray which is deviated least is
(a) the violet ray
(b) the red ray
(c) the green ray
(d) the yellow ray
Ans:b
(a) the violet ray
(b) the red ray
(c) the green ray
(d) the yellow ray
Ans:b
47. Magnetic storms are due to
(a) the rotation of the earth
(b) the revolution of the earth
(c) the rainy season
(d) the appearance off Sun spots
Ans:d
(a) the rotation of the earth
(b) the revolution of the earth
(c) the rainy season
(d) the appearance off Sun spots
Ans:d
48. For dynamo which one of the following statements is correct ?
(a) It converts the electrical energy into light energy
(b) It converts the kinetic energy into heat energy
(c) It converts the mechanical energy into electrical energy
(d) Jt converts the electrical energy into mechanical energy.
Ans:c
(a) It converts the electrical energy into light energy
(b) It converts the kinetic energy into heat energy
(c) It converts the mechanical energy into electrical energy
(d) Jt converts the electrical energy into mechanical energy.
Ans:c
49. In a transformer the immediate cause of the induced A. C. in the secondary coil is?
(a) a varying electric field
(b) a varying magnetic field
(e) a motion of the secondary coil
(d) efficiency of the operator
Ans:b
(a) a varying electric field
(b) a varying magnetic field
(e) a motion of the secondary coil
(d) efficiency of the operator
Ans:b
50.A dynamo actually acts as a?
(a) converter of energy
(b) source of electric charge
(c) source of magnetic charge
(d) source of energy
Ans:a
(a) converter of energy
(b) source of electric charge
(c) source of magnetic charge
(d) source of energy
Ans:a
.......................................................-------------------------------------..........................................................
Quiz MCQ Objective Question About Current Magnetic Field For Engineering Assistants in All India Radio ( Akashvani AIR) and Doordarshan (DD)
1. A current carrying coil is subjected to a uniform magnetic field. The coil will orient so that its
plane becomes ?
(a) inclined at 45° to the magnetic field
(b) inclined at any arbitrary angle to the
magnetic field
(c) parallel to the magnetic field
(d) perpendicular to magnetic field
plane becomes ?
(a) inclined at 45° to the magnetic field
(b) inclined at any arbitrary angle to the
magnetic field
(c) parallel to the magnetic field
(d) perpendicular to magnetic field
Ans:c
2. Tesla is the unit of
(a) magnetic flux
(b) magnetic field
(c) magnetic induction
(d) magnetic moment
Ans:b
(a) magnetic flux
(b) magnetic field
(c) magnetic induction
(d) magnetic moment
Ans:b
3. Energy in a current carrying coil is stored in the
form of ?
(a) electric field
(b) magnetic field
(c) dielectric strength
(d) heat
form of ?
(a) electric field
(b) magnetic field
(c) dielectric strength
(d) heat
Ans:b
4. The total charge induced in a conducting loop when it is moved in magnetic field depends on?
(a) the rate of change of magnetic flux
(b) initial magnetic flux only
(c) the total change in magnetic flux
(d) final magnetic flux only.
Ans:c
(a) the rate of change of magnetic flux
(b) initial magnetic flux only
(c) the total change in magnetic flux
(d) final magnetic flux only.
Ans:c
5. The magnetic induction at a point P which is at the distance of 4 cm from a long current carrying wire is 10-3 T. The field of induction at a distance 12 cm from the current will be ?
(a) 3.33 x 10-4 T
(b) 1.11x 10-4 T
(c) 3×10-3 T
(d) 9×10-3 T
(a) 3.33 x 10-4 T
(b) 1.11x 10-4 T
(c) 3×10-3 T
(d) 9×10-3 T
Ans:a
6. A charge moving with velocity v in X-direction is subjected to a field of magnetic induction in negative X-direction. As a result, the charge will
(a) remain unaffected
(b) start moving in a circular path in Y—Z plane
(c) retard along X-axis
(d) moving along a helical path around X-axis
Ans:a
(b) start moving in a circular path in Y—Z plane
(c) retard along X-axis
(d) moving along a helical path around X-axis
Ans:a
7. A uniform magnetic field acts right angles to the direction of motion of electrons. As a result, the electron moves in a circular path of radius 2cm. If the speed of electrons is doubled, then the radius of the circular path will be ?
(a)2.0 cm
(b) 0.5 cm
(c)4.0cm
(d) 1.0cm
(a)2.0 cm
(b) 0.5 cm
(c)4.0cm
(d) 1.0cm
Ans:c
8. A deuteron of kinetic energy 50 keV is describing a circular orbit of radius 0.5 metre in a plane perpendicular to magnetic field B. The kinetic energy of the proton that describes a circular orbit of radius 0.5 metre in the same plane with
the same B is
(a)25 keV
(b) 50 keV
(c)200 keV
(d) 100 keV
the same B is
(a)25 keV
(b) 50 keV
(c)200 keV
(d) 100 keV
Ans:d
9. A straight wire of length 0.5 metre and carrying a current of 1.2 ampere is placed in uniform magnetic field of induction 2 Tesla. The magnetic field is perpendicular to the length of the wire. The force on the wire is ?
(a) 2.4N
(b) 1.2N
(c) 3.0 N
(d) 2.0 N
Ans:b
(a) 2.4N
(b) 1.2N
(c) 3.0 N
(d) 2.0 N
Ans:b
10. To convert a galvanometer into an ammeter, one needs to connect a ?
(a) low resistance in parallel
(b) high resistance in parallel
(c) low resistance in series
(d) high resistance in series.
Ans:a
(a) low resistance in parallel
(b) high resistance in parallel
(c) low resistance in series
(d) high resistance in series.
Ans:a
11. A coil carrying electric current is placed in uniform magnetic field
(a) torque is formed
(B) e.m.f is induced
(c) both (a) and (b) are correct
(d) none of the above
Ans:a
(a) torque is formed
(B) e.m.f is induced
(c) both (a) and (b) are correct
(d) none of the above
Ans:a
12. The magnetic field at a distance ‘r’ from a long wire carrying current ‘i’ is 0.4 Tesla. The magnetic field at a distance ‘2r’ is ?
(a)0.2Tesla
(b) 0.8 Tesla
(c)0.1 Tesla
(d) 1.6 Tesla
Ans:a
(a)0.2Tesla
(b) 0.8 Tesla
(c)0.1 Tesla
(d) 1.6 Tesla
Ans:a
13. A electron enters a region where magnetic (B) and electric (E) fields are mutually
perpendicular, then ?
(a) it will always move in the direction of B
(b) it will always move in the direction of E
(c) it always possesses circular motion
(d) it can go un deflected also.
Ans:d
perpendicular, then ?
(a) it will always move in the direction of B
(b) it will always move in the direction of E
(c) it always possesses circular motion
(d) it can go un deflected also.
Ans:d
14. A straight wire of diameter 0.5 mm carrying a current of 1 A is replaced by another wire of I mm diameter carrying same current. The strength of magnetic field far away is?
(a) twice the earlier value
(b) same as the earlier value
(c) one-half of the earlier value
(d) one-quarter of the earlier value
(a) twice the earlier value
(b) same as the earlier value
(c) one-half of the earlier value
(d) one-quarter of the earlier value
Ans:b
15. At what distance from a long straight wire carrying a current of 12 A will the magnetic field
be equal to 3×10-6 Wb/metre Square
(a) 8×10-2 m
(b) 12×10-2 m
(c)18x 10-2 m
(d) 24×10-2 m
be equal to 3×10-6 Wb/metre Square
(a) 8×10-2 m
(b) 12×10-2 m
(c)18x 10-2 m
(d) 24×10-2 m
Ans:a
16. An electron moves in a circular orbit with a uniform speed v. It produces a magnetic field B at the centre of the circle. The radius of the circle is proportional to ?
(a) √(B/v)
(b) B/v
(c) √(v/B)
(d)v/B
(a) √(B/v)
(b) B/v
(c) √(v/B)
(d)v/B
Ans:d
17. A 10 eV electron is circulating in a plane at right angles to a uniform field at magnetic induction 10-4 Wb/m2 (= 1.0 gauss). The orbital radius of the electron is ?
(a) 12cm
(b) 16cm
(c) 11cm
(d) 18cm
Ans:c
(a) 12cm
(b) 16cm
(c) 11cm
(d) 18cm
Ans:c
18. A galvanometer acting as a voltmeter will have?
(a) a low resistance in series with its coil.
(b) a high resistance in parallel with its coil
(c) a high resistance in series with its coil
(d) a low resistance in parallel with its coil
Ans:c
(b) a high resistance in parallel with its coil
(c) a high resistance in series with its coil
(d) a low resistance in parallel with its coil
Ans:c
19. A beam of electrons is moving with constant velocity in a region having simultaneous perpendicular electric and magnetic fields of strength 20 Vm-1 and 0.5 T respectively at right angles to the direction of motion of the electrons. Then the velocity of electrons must be?
(a) 8m/s
(b) 20 m/s
(c) 40m/s
(d) 1/40 m/s
(a) 8m/s
(b) 20 m/s
(c) 40m/s
(d) 1/40 m/s
Ans:c
20. A galvanometer of resistance 20 Ohms gives full scale deflection with a current of 0.004 A. To convert it into an ammeter of range 1 A, the required shunt resistance should be?
(a) 0.38 Ohms
(b) 0.21 Ohms
(c) 0.08 Ohms
(d) 0.05 Ohms
Ans:c
(b) 0.21 Ohms
(c) 0.08 Ohms
(d) 0.05 Ohms
Ans:c
21. A long solenoid carrying a current produces a magnetic field B along its axis. If the current is doubled and the number of turns per cm is halved, the new value of the magnetic field is ?
(a) 4B
(b) B/2
(c) B
(d) 2B
Ans:c
(a) 4B
(b) B/2
(c) B
(d) 2B
Ans:c
22. A positively charged particle moving due east enters a region of uniform magnetic field directed vertically upwards. The particle will
(a) continue to move due east
(b) move in a circular orbit with its speed unchanged
(c) move in a circular orbit with its speed increased
(d) gets deflected vertically upwards.
(a) continue to move due east
(b) move in a circular orbit with its speed unchanged
(c) move in a circular orbit with its speed increased
(d) gets deflected vertically upwards.
Ans:b
23. Two long parallel wires are at a distance of 1 metre. Both of them carry one ampere of current The force of attraction per unit length between the two wires is?
(a)2 x10-7 N/m
(b) 2 x10-8 N/m
(c) 5×10-8 N/m
(d)10-7 N/m
23. Two long parallel wires are at a distance of 1 metre. Both of them carry one ampere of current The force of attraction per unit length between the two wires is?
(a)2 x10-7 N/m
(b) 2 x10-8 N/m
(c) 5×10-8 N/m
(d)10-7 N/m
Ans:a
24. A galvanometer having a resistance of 8 ohms is shunted by a wire of resistance 2 ohms. If the total current is 1 amp, the part of it passing through the shunt will be?
(a)0.25 amp
(b) 0.8 amp
(c)0.2 amp
(d) 0.5 amp
(a)0.25 amp
(b) 0.8 amp
(c)0.2 amp
(d) 0.5 amp
Ans:b
25. A coil of one turn is made of a wire of certain length and then from the same length a coil of two turns is made. If the same current is passed in both the cases, then the ratio of the magnetic inductions at their centres will be?
(a)2:1
(b)1:4
(c)4:1
(d)1:2
Ans:b
(a)2:1
(b)1:4
(c)4:1
(d)1:2
Ans:b
26. Magnetic field intensity in the centre of coil of 50 turns, radius 0.5 m and carrying a current of
2A is ?
(a) 0.5 x 10-5 T
(b) 1.25x 10-4 T
(c) 3x 10-5 T
(c) 4 x 10-5 T
2A is ?
(a) 0.5 x 10-5 T
(b) 1.25x 10-4 T
(c) 3x 10-5 T
(c) 4 x 10-5 T
Ans:b
27. When a proton is accelerated through I V, then its kinetic energy will be?
(a)1840 eV
(b) 13.6eV
(c)1 eV
(d) 0.54eV
(a)1840 eV
(b) 13.6eV
(c)1 eV
(d) 0.54eV
Ans:c
28. If a long hollow copper pipe carries a current,thin magnetic field is produced
(a)inside the pipe only
(b)outside the pipe only
(c)both inside and outside the pipe
(d) no where
(a)inside the pipe only
(b)outside the pipe only
(c)both inside and outside the pipe
(d) no where
Ans:b
29. A charged particle moves through a magnetic field in a direction perpendicular to it. Then the
(a) velocity remains unchanged
(b) speed of the particle remains unchanged
(c) direction of the particle remains unchanged
(d) acceleration remains unchanged
Ans:b
(b) speed of the particle remains unchanged
(c) direction of the particle remains unchanged
(d) acceleration remains unchanged
Ans:b
30. Two long parallel wires P and Q are both perpendicular to the plane of the paper with distance of 5 m between them. If P and Q carry current of 2.5 amp and 5 amp respectively in the same direction, then the magnetic field at a point half-way between the wires is ?
(a)3µ/2∏
(b)µ/∏
(c)√3µ/2∏
(d)µ/2∏
Ans:a
(b)µ/∏
(c)√3µ/2∏
(d)µ/2∏
Ans:a
31. A proton moving with a velocity 3 x 105 m/s enters a magnetic field of 0.3 Tesla at an angle of 30° with the field. The radius of curvature of its path will be (e/m for proton – 108 C/kg)
(a)2cm
(b) 0.5 cm
(c)0.02 cm
(d) 1.25 cm
(a)2cm
(b) 0.5 cm
(c)0.02 cm
(d) 1.25 cm
Ans:b
32. A charged particle of charge q and mass m enters perpendicularly in a magnetic field B. Kinetic energy of the particle is E; then frequency of rotation is?
(a)qB/m∏
(b) qB/2m∏
(c)qBE/2m∏
(d) qB/2E∏
(a)qB/m∏
(b) qB/2m∏
(c)qBE/2m∏
(d) qB/2E∏
Ans:b
33. A galvanometer can be converted into a voltmeter by connecting?
(a) A high resistance in parallel
(b) A low resistance in series
(c) A high resistance in series
(d) A low resistance in parallel
Ans:c
(a) A high resistance in parallel
(b) A low resistance in series
(c) A high resistance in series
(d) A low resistance in parallel
Ans:c
34. A wire carries a current. Maintaining the same current it is bent first to form a circular plane coil of one turn which produces a magnetic field B at the centre of the coil. The same length is now bent more sharply to give a double loop of smaller radius. The magnetic field at the centre of the double loop, caused by the same current is ?
(a)4B
(b) B /4
(c) B/2
(d) 2B
Ans:a
(a)4B
(b) B /4
(c) B/2
(d) 2B
Ans:a
35.A bar magnet is oscillating in earth’s magnetic field with a period T. What happens to its period of motion, if its mass is quadruped ?
(a) Motion remains simple harmonic with new period =T/2
(b) Motion remains simple harmonic with new period = 2 T
(c) Motion remains simple harmonic with new period =4T
(d) Motion remains simple harmonic and the period stays nearly constant
Ans:b
(a) Motion remains simple harmonic with new period =T/2
(b) Motion remains simple harmonic with new period = 2 T
(c) Motion remains simple harmonic with new period =4T
(d) Motion remains simple harmonic and the period stays nearly constant
Ans:b
36. The work done in turning a magnet of magnetic moment M by an angle of 90° from the meridian, is n times the corresponding work done to turn it through an angle of 60°.
The value of n is given by
(a)2
(b) 1
(c) 0.5
(d) 0.25
Ans:a
The value of n is given by
(a)2
(b) 1
(c) 0.5
(d) 0.25
Ans:a
37 . For protecting a sensitive equipment from the external electric arc, it should be ?
(a) Wrapped with insulation around it when passing current through it
(b) Placed inside an iron can
(c) Surrounded with fine copper sheet
(d) Placed inside an aluminium can
Ans:b
(a) Wrapped with insulation around it when passing current through it
(b) Placed inside an iron can
(c) Surrounded with fine copper sheet
(d) Placed inside an aluminium can
Ans:b
38. If a diamagnetic substance is brought near north or south pole of a bar magnet, it is?
(a) attracted by the poles
(b) repelled by the poles
(c) repelled by north pole and attracted by the south pole
(d) attracted by the north pole and repelled by the south pole
(a) attracted by the poles
(b) repelled by the poles
(c) repelled by north pole and attracted by the south pole
(d) attracted by the north pole and repelled by the south pole
Ans:b
39. Current i is flowing in a coil of area A and number of turns N, then magnetic moment of
the coil is M= ?
the coil is M= ?
(a) NiA
(b) Ni/A
(c)Ni/√A
(d) N2Ai
(b) Ni/A
(c)Ni/√A
(d) N2Ai
Ans:a
40. Two magnets of magnetic moments M and 2M are placed in a vibration magnetometer, with the identical poles in the same direction. The time period of vibration is T1. If the magnets are placed with opposite poles together and vibrate with time period T2 then ?
(a) T2 is infinite
(b) T2=T1
(c)T2>T1
(d) T2 is less than T1
(a) T2 is infinite
(b) T2=T1
(c)T2>T1
(d) T2 is less than T1
Ans:c
41. A diamagnetic material in a magnetic field moves
(a) perpendicular to the field
(b) from stronger to the weaker pans of the field
(c) from weaker to the stronger parts of the field
(d) in none of the above directions
Ans:b
42. According to Curie’s law, the magnetic susceptibility of a substance at an absolute
temperature T is proportional to?
(a) T2
(b) 1/T
(c) T
(d) 1/T2
41. A diamagnetic material in a magnetic field moves
(a) perpendicular to the field
(b) from stronger to the weaker pans of the field
(c) from weaker to the stronger parts of the field
(d) in none of the above directions
Ans:b
42. According to Curie’s law, the magnetic susceptibility of a substance at an absolute
temperature T is proportional to?
(a) T2
(b) 1/T
(c) T
(d) 1/T2
Ans:b
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Objective MCQ Questions on Solids and Semiconductor devices Like Diodes transistors Amplifiers
Basic Electronics Quiz
Semiconductor Quiz
Basic Electronics Quiz
Semiconductor Quiz
1.A p-n junction is said to be forward biased, when
(a) the positive pole of the battery is joined to the p-semiconductor and negative pole to the n-semiconductor
(b) the positive pole of the battery is joined to the n-semiconductor and negative pole of the battery is joined to the p-semiconductor
(c) the positive pole of the battery is connected to n- semiconductor and p- semiconductor
(d) a mechanical force is applied in the forward direction
(a) the positive pole of the battery is joined to the p-semiconductor and negative pole to the n-semiconductor
(b) the positive pole of the battery is joined to the n-semiconductor and negative pole of the battery is joined to the p-semiconductor
(c) the positive pole of the battery is connected to n- semiconductor and p- semiconductor
(d) a mechanical force is applied in the forward direction
Ans :a
2. At absolute zero, Si acts as ?
(a) non-metal
(b) metal
(c) insulator
(d) none of these
(b) metal
(c) insulator
(d) none of these
Ans :a
3. When N-type semiconductor is heated ?
(a) number of electrons increases while that of holes decreases
(b) number of holes increases while that of electrons decreases
(c) number of electrons and holes remain same
(d) number of electron and holes increases equally.
Ans :d
(a) number of electrons increases while that of holes decreases
(b) number of holes increases while that of electrons decreases
(c) number of electrons and holes remain same
(d) number of electron and holes increases equally.
Ans :d
4. Radiowaves of constant amplitude can be generated with
(a) FET
(b) filter
(c) rectifier
(d) oscillator
(a) FET
(b) filter
(c) rectifier
(d) oscillator
Ans :d
5. In a common base amplifier the phase difference between the input signal voltage and the output
voltage is ?
(a) 0
(b) pi/4
(c)pi/2
(d) p
Ans :d
6. When a triode is used as an amplifier the phase difference between the input signal voltage and
the output is ?
(a) 0
(b)pi
(c) pi/2
(d)pi/4
voltage is ?
(a) 0
(b) pi/4
(c)pi/2
(d) p
Ans :d
6. When a triode is used as an amplifier the phase difference between the input signal voltage and
the output is ?
(a) 0
(b)pi
(c) pi/2
(d)pi/4
Ans :b
7. The depletion layer in the P-N junction region is
caused by?
(a) drift of holes
(b) diffusion of charge carriers
(c) migration of impurity ions
(d) drift of electrons
caused by?
(a) drift of holes
(b) diffusion of charge carriers
(c) migration of impurity ions
(d) drift of electrons
Ans: b
8. The following truth table corresponds to which Logic gate
8. The following truth table corresponds to which Logic gate
| A | B | Output |
| 0 | 0 | 0 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 1 |
(a)NAND
(b) OR
(c)AND
(d) XOR
(b) OR
(c)AND
(d) XOR
Ans :b
9. To use a transistor as an amplifier
(a) The emitter base junction is forward biased and the base collector junction is reversed biased
(b) no bias voltage is required
(c) both junction are forward biased
(d) both junctions are reversed biased.
(a) The emitter base junction is forward biased and the base collector junction is reversed biased
(b) no bias voltage is required
(c) both junction are forward biased
(d) both junctions are reversed biased.
Ans :a
10. Which one of the following is the weakest kind of the bonding in solids
(a) ionic
(b) metallic
(c) Vander Walls
(d) covalent
Ans :c
(a) ionic
(b) metallic
(c) Vander Walls
(d) covalent
Ans :c
11.For amplification by a triode, the signal to be amplified is given to
(a) the cathode
(b) the grid
(c) the glass-envelope
(d) the anode
Ans :b
(a) the cathode
(b) the grid
(c) the glass-envelope
(d) the anode
Ans :b
12. A piece of copper and other of germanium are cooled from the room temperature to 80K, then
(a) resistance of each will increase
(b) resistance of copper will decrease
(c) the resistance of copper will increase while that of germanium will decrease
(d) the resistance of copper will decrease while that of germanium will increase
Ans:d
(b) resistance of copper will decrease
(c) the resistance of copper will increase while that of germanium will decrease
(d) the resistance of copper will decrease while that of germanium will increase
Ans:d
13. Diamond is very hard because ?
(a) it is covalent solid
(b) it has large cohesive energy
(c) high melting point
(d) insoluble in all solvents
Ans:b
(a) it is covalent solid
(b) it has large cohesive energy
(c) high melting point
(d) insoluble in all solvents
Ans:b
14. The part of the transistor which is heavily doped to produce large number of majority carriers is
(a) emitter
(b) base
(c) collector
(d) any of the above depending upon the nature of transistor
(b) base
(c) collector
(d) any of the above depending upon the nature of transistor
Ans:a
15. An Oscillator is nothing but an amplifier with
15. An Oscillator is nothing but an amplifier with
(a) positive, feedback
(b) negative feedback
(c)large gain
(d) no feedback
Ans:a
(b) negative feedback
(c)large gain
(d) no feedback
Ans:a
17. When a P-N junction diode is reverse biased the flow of current across the junction is mainly due
to
(a) diffusion of charge
(b) drift charges
(c) depends on the nature o material
(d) both drift and diffusion of charges
to
(a) diffusion of charge
(b) drift charges
(c) depends on the nature o material
(d) both drift and diffusion of charges
Ans:b
18. Which of the following gates corresponds to the truth table given below?
| A | B | Output |
| 1 | 1 | 0 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 0 | 0 | 1 |
(a) NAND
(b) OR
(c) AND
(d) XOR
(b) OR
(c) AND
(d) XOR
Ans:a
19. Which of the following, when added as an impurity, into the silicon, produces n-type semi conductor
(a)Phosphorous
(b) Aluminium
(c)Magnesium
(d) both ‘b’ and ‘c’
(a)Phosphorous
(b) Aluminium
(c)Magnesium
(d) both ‘b’ and ‘c’
Ans:a
20. The current gain for a transistor working as common-base amplifier is 0.96. If the emitter current is 7.2 mA, then the base current is
(a)0.29mA
(b)0.35mA
(c)0.39 mA
(d) 0.43 mA
(a)0.29mA
(b)0.35mA
(c)0.39 mA
(d) 0.43 mA
Ans:a
21. When a n-p-n transistor is used as an amplifier then ?
(a) the electrons flow from emitter to collector
(b) the holes flow from emitter to collector
(c) the electrons flow from collector to emitter
(d) the electrons flow from battery to emitter
Ans:a
21. When a n-p-n transistor is used as an amplifier then ?
(a) the electrons flow from emitter to collector
(b) the holes flow from emitter to collector
(c) the electrons flow from collector to emitter
(d) the electrons flow from battery to emitter
Ans:a
22. When arsenic is added as an impurity to silicon, the resulting material is?
(a) n-type semiconductor
(b) p-type semiconductor
(c) n-type conductor
(d) Insulator
(a) n-type semiconductor
(b) p-type semiconductor
(c) n-type conductor
(d) Insulator
Ans:a
23. To obtain a p-type germanium semiconductor,it must be doped with ?
(a)arsenic
(b)antimony
(c)indium
(d)phosphorus
Ans: c
(a)arsenic
(b)antimony
(c)indium
(d)phosphorus
Ans: c
24. A semi-conducting device is connected in a series circuit with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops to almost zero. The device may be
(a) A p-n junction
(b) An intrinsic semi-conductor
(c) A p-type semi-conductor
(d) An n-type semi-conductor
(a) A p-n junction
(b) An intrinsic semi-conductor
(c) A p-type semi-conductor
(d) An n-type semi-conductor
Ans:a
25. The transfer ratio beta of a transistor is 50. The input resistance of the transistor when used in the common emitter configuration is 1 kOhm. The peak value of the co current for an A.C. input voltage of 0.01 V peak is ?
(a)100 microA
(b) 0.01 mA
(c)0.25 mA
(d) 500 microA
Ans:d
(a)100 microA
(b) 0.01 mA
(c)0.25 mA
(d) 500 microA
Ans:d
26. The cause of the potential barrier in a p-n diode is ?
(a) Depletion of positive charges near the junction
(b) Concentration of positive charges near the junction
(c) Depletion of negative charges near the junction
(d) Concentration of positive and negative charges near the junction
Ans:d
(a) Depletion of positive charges near the junction
(b) Concentration of positive charges near the junction
(c) Depletion of negative charges near the junction
(d) Concentration of positive and negative charges near the junction
Ans:d
27. In forward bias, the width of potential barrier in a p-n junction diode?
(a)increases
(b) decreases
(c) remains constant
(d) first increases then decreases
(a)increases
(b) decreases
(c) remains constant
(d) first increases then decreases
Ans:b
28. A depletion lay consists of?
(a)electrons
(b) protons
(c)mobile ions
(d) immobile ions
(a)electrons
(b) protons
(c)mobile ions
(d) immobile ions
Ans:d
29. Which of the following when added acts as an impurity into silicon produced n-type semi
conductor?
(a)P
(b) Al
(c)B
(d) Mg
29. Which of the following when added acts as an impurity into silicon produced n-type semi
conductor?
(a)P
(b) Al
(c)B
(d) Mg
Ans:a
30. In a junction diode, the holes are due to
(a) protons
(b) extra electrons
(c) neutrons
(d) missing electrons
(a) protons
(b) extra electrons
(c) neutrons
(d) missing electrons
Ans:d
31. The intrinsic semiconductor becomes an insulator at
(a)0°C
(b)0K
(c) 300K
(d) —100°C
(a)0°C
(b)0K
(c) 300K
(d) —100°C
Ans:b
32. For a common emitter circuit if IC/IE = 0.98 then current gain for common emitter circuit will be
(a)49
(b)98
(e)4.9
(d) 25.5
Ans:a
(a)49
(b)98
(e)4.9
(d) 25.5
Ans:a
33. In a p-n junction
(a) The potential of the p and n sides becomes higher alternately
(b) The p side is at higher electrical potential than the n side
(c) The n side is at higher electrical potential than the p side
(d) Both the p and n sides are at the same potential
(a) The potential of the p and n sides becomes higher alternately
(b) The p side is at higher electrical potential than the n side
(c) The n side is at higher electrical potential than the p side
(d) Both the p and n sides are at the same potential
Ans:b
34. In the case of a common emitter transistor amplifier the ratio of the collector current to the emitter current Ic/Ie is 0.96. The current gain of the amplifier is ?
(a)6
(b)48
(c) 24
(d) 12
(a)6
(b)48
(c) 24
(d) 12
Ans:c
35. if a full wave rectifier circuit is operating from 5oHz mains, the fundamental frequency in the
tipple will be
(a)100Hz
(b) 25Hz
(c)50Hz
(d) 70.7 Hz
tipple will be
(a)100Hz
(b) 25Hz
(c)50Hz
(d) 70.7 Hz
Ans:a
36. A n-p-n transistor conducts when ?
(a) both collector and emitter are negative with respect to, the base
(b) both collector and emitter are positive with respect to the base
(c) collector is positive and emitter is negative with to the base
(d) collector is positive and emitter is at same potential as the base
36. A n-p-n transistor conducts when ?
(a) both collector and emitter are negative with respect to, the base
(b) both collector and emitter are positive with respect to the base
(c) collector is positive and emitter is negative with to the base
(d) collector is positive and emitter is at same potential as the base
Ans:c
37. Barrier potential of a p-n junction diode does not depend on?
(a)doping density
(b) diode design
(c)temperature
(d) forward bias
(a)doping density
(b) diode design
(c)temperature
(d) forward bias
Ans:b
38. Reverse bias applied to a junction diode
(a) increases the minority carrier current
(b) lowers the potential barrier
(c) raises the potential barrier
(d) increases the majority carrier current
(a) increases the minority carrier current
(b) lowers the potential barrier
(c) raises the potential barrier
(d) increases the majority carrier current
Ans:c
39. In semiconductors at a room temperature
(a) the conduction band is completely empty
(b) the valence band is partially empty and the conduction band is partially filled
(c) the valence band is completely filled and the conduction band is partially filled
(d) the valence band is completely filled
(b) the valence band is partially empty and the conduction band is partially filled
(c) the valence band is completely filled and the conduction band is partially filled
(d) the valence band is completely filled
Ans:c
40. The output of OR gate is 1 when?
(a) if either input is zero
(b) if both inputs are zero
(c) if either or both inputs are 1
(d) only if both inputs are I
Ans:c
(a) if either input is zero
(b) if both inputs are zero
(c) if either or both inputs are 1
(d) only if both inputs are I
Ans:c
41. In a p-n junction photo cell, the value of the photo-electromotive force produced by monochromatic light is proportional to ?
(a) the voltage applied at the p-n junction
(b) the barrier voltage at the p-n junction
(c) the intensity of the light falling on the cell
(d) the frequency of the light falling on the cell
Ans:c
(a) the voltage applied at the p-n junction
(b) the barrier voltage at the p-n junction
(c) the intensity of the light falling on the cell
(d) the frequency of the light falling on the cell
Ans:c
42. Choose the only false statement from the following.
(a) in conductors the valence and conduction bands may overlap.
(b) Substances with energy gap of the order of 10 eV are insulators.
(c) The resistivity of a semiconductor increases with increase in temperature.
(d) The conductivity of a semiconductor increases with increase in temperature.
(a) in conductors the valence and conduction bands may overlap.
(b) Substances with energy gap of the order of 10 eV are insulators.
(c) The resistivity of a semiconductor increases with increase in temperature.
(d) The conductivity of a semiconductor increases with increase in temperature.
Ans:c
43. Carbon, Silicon and Germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy band gaps represented by (Eg)C, (Eg)Si and (Eg)Gerespectively. Which one of the following relationship is true in their case?
(a) (Eg)C> (Eg)Si
(b) (Eg)C< (Eg)Si
(c) (Eg)C=(Eg)Si
(d) (Eg)C< (Eg)Ge
Ans:a
44. Application of a forward bias to a p—n junction
(a) widens the depletion zone.
(b) increases the potential difference across the depletion zone.
(c) increases the number of donors on the n side.
(d) increases the electric field in the depletion zone.
(a) (Eg)C> (Eg)Si
(b) (Eg)C< (Eg)Si
(c) (Eg)C=(Eg)Si
(d) (Eg)C< (Eg)Ge
Ans:a
44. Application of a forward bias to a p—n junction
(a) widens the depletion zone.
(b) increases the potential difference across the depletion zone.
(c) increases the number of donors on the n side.
(d) increases the electric field in the depletion zone.
Ans:c
45. Zener diode is used for?
(a) Amplification
(b) Rectification
(c) Stabilisation
(d) Producing oscillations in an oscillator
(a) Amplification
(b) Rectification
(c) Stabilisation
(d) Producing oscillations in an oscillator
Ans:c
................................................---------------------------------------............................................................
ONGC GT 2010 Model test paper Electrical Engineering
1. A circular loop has its radius increasing at a rate of 2 m/s The loop Is placed perpendicular to a constant magnetic field of 0.1 Wb/m 2. When the radius of the loop is m, the emf induced in the loop
will be
(a) 0.8 ?V
1. A circular loop has its radius increasing at a rate of 2 m/s The loop Is placed perpendicular to a constant magnetic field of 0.1 Wb/m 2. When the radius of the loop is m, the emf induced in the loop
will be
(a) 0.8 ?V
(b) 0.4 ?V
(c) 0.2?V
(c) 0.2?V
(d) zero
2.A type I superconductor maintained, at a temperature T < Tc is subjected to a magnetic field
H< Hc
2.A type I superconductor maintained, at a temperature T < Tc is subjected to a magnetic field
H< Hc
The superconductor will exhibit
(a) perfect diamagnetism .
(b) partial diamagnetism
(c) perfect paramagnetism
(d) partial paramagnetism
(a) perfect diamagnetism .
(b) partial diamagnetism
(c) perfect paramagnetism
(d) partial paramagnetism
3. The magnetic susceptibility of a paramagnetic material is
(a)less than zero
(b) less than one but positive
(c)greater than one
(d) equal to zero
(a)less than zero
(b) less than one but positive
(c)greater than one
(d) equal to zero
4. Magnetostriction is a phenomenon whereby the magnetisation of a ferromagnetic material leads to
a change in
(a)relative permeability
(b) physical dimensions
(c)spontaneous magnetisation
(d) magnetic susceptibility
a change in
(a)relative permeability
(b) physical dimensions
(c)spontaneous magnetisation
(d) magnetic susceptibility
5. Consider the following statements:
I: Any function in ‘s’ which can be expressed as a ratio of any two arbitrary polynomials In ‘s’ can be released as a driving —point function of a passive network
II: Any function in ‘s’ which can be expressed as a ratio of two arbitrary polynomials in ‘s’, Is positive real function.
Of these statements
(a)both I and II are true
(b) I is true but II is false
(c)both I and II are false
(d) I is false but II is true
I: Any function in ‘s’ which can be expressed as a ratio of any two arbitrary polynomials In ‘s’ can be released as a driving —point function of a passive network
II: Any function in ‘s’ which can be expressed as a ratio of two arbitrary polynomials in ‘s’, Is positive real function.
Of these statements
(a)both I and II are true
(b) I is true but II is false
(c)both I and II are false
(d) I is false but II is true
6. Consider the following polynomials:
1. s4+7s3+17s 2+17s+6
2. s4+11s3+41s 2+61s+30
3.s4+s3+2s 2+3s+2
Among these polynomials, those which are Hurwitz would include
(a)1 and 2
(b) 2 and 3
(c)1 and 3
(d) 1,2 and 3
7.Unit ramp has Laplace transform
(a)s
(b) 1
(c)1/s
(d) 1/s2
1. s4+7s3+17s 2+17s+6
2. s4+11s3+41s 2+61s+30
3.s4+s3+2s 2+3s+2
Among these polynomials, those which are Hurwitz would include
(a)1 and 2
(b) 2 and 3
(c)1 and 3
(d) 1,2 and 3
7.Unit ramp has Laplace transform
(a)s
(b) 1
(c)1/s
(d) 1/s2
8.A system is represented by dy/dt+ 2y =4t u(t)
The ramp component in the forced response will be
(a)t u(t)
(b) 2t u(t)
(c)3t u(t)
(d) 4t u(t)
The ramp component in the forced response will be
(a)t u(t)
(b) 2t u(t)
(c)3t u(t)
(d) 4t u(t)
9. The Laplace transform of the function i(t) is I(s) = (10s+4)/(s(s+1)(s2 +4s+5))
Its final value will be
(a) 4/5
(b) 5/4
(c) 4
(d) 5
(a) 4/5
(b) 5/4
(c) 4
(d) 5
10 The limiting errors of measurement of power consumed b and the current passing through a a resistance are + 1.5% and ± 1% respectively. The limiting error of measurement of resistance will then be
(a)± 0.5%
(b) ± 1.0%
(c)±2.5%
(d) ±3%
(a)± 0.5%
(b) ± 1.0%
(c)±2.5%
(d) ±3%
Answers:
1:b
2:a
3:b
4:b
5:c
6:a
7:d
8:b
9:a
10:d
2:a
3:b
4:b
5:c
6:a
7:d
8:b
9:a
10:d
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