7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 1/20

MCQs in EC, Electrical,Electronics,and

Computer science Engineering 

1. When four resistances of 2W 1W; 5W 2W; 10W 5W and 15W 10 W are connected in parallel, the greatest power is absorbed by

  2 W, 1 W  5 W, 2 W  10 W, 5W  15 W, 10 W

2. A moving coil instrument has a resistance of 10 W and gives full scale deflection when

carrying a current of 50 mA. To measure current upto 100 A, we will have to connect

  10 W resistance in series  10 W resistance in parallel  10/1999 W resistance in series  10/1999 W resistance in parallel

3. The ripple voltage in the output of a single phase half wave rectifier with 10 V rectified dcvoltage with resistive load and without filter will be

  12.1 volt  1.21 volt  0.482 volt  4.82 volt

4. The transformer connection which has gained considerable popularity to serve 3-phaseequipment and single phase lighting load is

  Star/Star   Delta/Delta  Delta/Star 

  Star/Delta

5. Transformer oil tester is used to know

  Permittivity  Permeability  Dielectric strength  Resistance of the oil

6. Plate separation of a parallel plate air capacitor is reduced keeping the voltageconstant. The energy stored in the capacitor shall

  Increase

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 2/20

  Decrease  Remain constant  Remain zero

7. 1 Ampere of current is defined as

  1 volt/sec  1 coulomb/sec  1 ohm/second  1 coulomb

8. The synchronous motor can be used as a capacitor 

  By increasing excitation  By decreasing excitation  By increasing speed  By decreasing speed

9. The actual speed of an induction motor is always

  Less than synchronous speed  More than synchronous speed  Equal to synchronous speed   None of the above.

10. The purpose of connecting a capacitor in flourescent tube circuit is

  To increase switching on time  To decrease switching off time  To increase power factor   To decrease power consumption

11. The condition for parallel operation of two inverters is

  Amplitude of voltages should be same.  Frequency of voltages should be same.  Both the voltages should be in same phase.

  All the three above.

12. A 60 Hz, 2 pole alternator should run at

  a. 3000 r.p.m. c. 1500 r.p.m.   b. 3600 r.p.m. d. 1800 r.p.m.

13. The purpose of a governer in a DG set is

  To regulate the speed.  To regulate the voltage

  To regulate the power   To regulate the current.

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 3/20

14. A S C R can conduct

  In one direction only.  In both directions.  Only when gate is triggered.

   None of the above.

15. The cut-in voltage of a silicon diode is approx.

  0.7 volt  0.3 volt  1.4 volt   None of the above.

16. The step Recovery Diode is used as

  Frequency adder   Frequency subtractor   Frequency multiplier    None of the above.

17. The isolation between input and output in case of opto coupler is of the order of 

  10 Ohms  1010 ohms  103 ohms   None of the above.

18. The transistor configuration to connect 4 W speaker with 600 W output impedance audioamplifier is

  Common Emitter   Common Base  Common Collector    None of the above.

19. Beta cut-off frequency of a transistor is the frequency at which the Beta is

  0.707 of low frequency value  Zero  Equal to low frequency value   None of the above.

20. Which of the following amplifier has the least distortion.

  Class E  Class D  Class C

  Class A

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 4/20

21. Pinch off voltage of a J FET is the drain to source voltage above which drain current.

  Increases  Decreases  Remains constant

  Becomes zero

22. Decimal equivalent of binary 1111 1111 1111 1111 is

  16,384  65,536  1000000   None of the above.

23. A l/2 dipole aerial is used for 

  MW  SW  Microwave   None of the above.

24. TCXO is preferred over LC oscillator because

  TCXO is more stable.  TCXO gives more power   TCXO is linear.   None of the above.

25. The angular velocity of geo-stationary satellite is

  Equal to the angular velocity of earth.  Less than the angular velocity of earth.  More than the angular velocity of earth   None of the above.

26. The battery operated pre-amplifier with a consumption of 10 Watts can work on batteryof 12 volt, 100 AH having efficiency of 50% for 

  120 hrs.  60 hrs.  100 hrs.  10 hrs.

27. Low pass filter with cut off frequency of 100 kHz and high pass filter with cut off frequency of 50 kHz are connected in tandem, the resultant filter is

  Low pass filter with cut off frequency of 100 kHz  High pass filter with cut off frequency of 50 kHz

  Band pass filter with pass band from 50 kHz to 100 kHz.   None of the above.

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 5/20

28. In case of oil fire, the fire extinguisher used is

  Soda Acid  Foam  Carbon dioxide

  Carbon Tetra chloride

29.The output of a 2-input NAND gate with high at both the inputs will be

  High  Low  High & low   None of the above.

30. The input impedance of an op-amp is

  High  Low  Medium   None of the above

Answers 

1(a), 2 (d), 3 (a), 4 (c), 5 (c) 6 (a) 7 (b) 8 (a) 9 (a) 10 (c) 11 (d) 12 (c) 13 (a) 14 (a) 15 (a)

16 (c) 17 (b) 18 (c) 19 (a) 20 (d) 21 (c) 22 (b) 23 (b) 24 (a) 25 (a) 26 (b) 27 (c) 28 (b) 29 (b)30 (a).

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 6/20

 

MCQs in Electricity & Electronics test paper 

1.When four resistances of 2 1W; 5 2W; 10 5W and 15 10 W are connected inparallel, the greatest power is absorbed by

  2 , 1 W

  5 , 2 W

  10 , 5W

  15 , 10 W 

2. A moving coil instrument has a resistance of 10 and gives full scale deflection whencarrying a current of 50 mA. To measure current upto 100 A, we will have to connect

  10 resistance in series   10 resistance in parallel   10/1999 resistance in series   10/1999 resistance in parallel 

3. The ripple voltage in the output of a single phase half wave rectifier with 10 V rectified dcvoltage with resistive load and without filter will be

  12.1 volt   1.21 volt   0.482 volt   4.82 volt 

4. The transformer connection which has gained considerable popularity to serve 3-phaseequipment and single phase lighting load is

  Star/Star    Delta/Delta   Delta/Star    Star/Delta 

5. Transformer oil tester is used to know

  Permittivity  

Permeability   Dielectric strength   Resistance of the oil 

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 7/20

6. Plate separation of a parallel plate air capacitor is reduced keeping the voltageconstant. The energy stored in the capacitor shall

  Increase   Decrease 

  Remain constant   Remain zero 

7. 1 Ampere of current is defined as

  1 volt/sec   1 coulomb/sec   1 ohm/second   1 coulomb 

8. The synchronous motor can be used as a capacitor 

  By increasing excitation   By decreasing excitation   By increasing speed   By decreasing speed 

9. The actual speed of an induction motor is always

  Less than synchronous speed   More than synchronous speed   Equal to synchronous speed   None of the above. 

10. The purpose of connecting a capacitor in flourescent tube circuit is

  To increase switching on time   To decrease switching off time   To increase power factor    To decrease power consumption 

11. The condition for parallel operation of two inverters is

   Amplitude of voltages should be same.   Frequency of voltages should be same.   Both the voltages should be in same phase.    All the three above. 

12. A 60 Hz, 2 pole alternator should run at

  3000 r.p.m.   1500 r.p.m.   3600 r.p.m.   1800 r.p.m.

13.The purpose of a governer in a DG set is

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 8/20

  To regulate the speed.   To regulate the voltage   To regulate the power    To regulate the current. 

14. A S C R can conduct

  In one direction only.   In both directions.   Only when gate is triggered.   None of the above. 

15.The cut-in voltage of a silicon diode is approx.

  0.7 volt   0.3 volt   1.4 volt   None of the above.

16. The step Recovery Diode is used as

  Frequency adder    Frequency subtractor    Frequency multiplier    None of the above. 

17. The isolation between input and output in case of opto coupler is of the order of 

  10 Ohms  1010 ohms   103 ohms  None of the above. 

18. The transistor configuration to connect 4 speaker with 600 output impedance audioamplifier is

  Common Emitter    Common Base   Common Collector    None of the above.

19. Beta cut-off frequency of a transistor is the frequency at which the Beta is 

  0.707 of low frequency value   Zero 

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 9/20

  Equal to low frequency value   None of the above. 

20. Which of the following amplifier has the least distortion.

  Class E   Class D   Class C   Class A 

21. Pinch off voltage of a J FET is the drain to source voltage above which drain current.

  Increases   Decreases   Remains constant   Becomes zero

22. Decimal equivalent of binary 1111 1111 1111 1111 is

  16,384   65,536   1000000   None of the above.

23. A /2 dipole aerial is used for 

  MW   SW 

  Microwave   None of the above.

24. TCXO is preferred over LC oscillator because

  TCXO is more stable.   TCXO gives more power    TCXO is linear.   None of the above. 

25. The angular velocity of geo-stationary satellite is

  Equal to the angular velocity of earth.   Less than the angular velocity of earth.   More than the angular velocity of earth   None of the above.

26. The battery operated pre-amplifier with a consumption of 10 Watts can work on batteryof 12 volt, 100 AH having efficiency of 50% for 

  120 hrs.   60 hrs.   100 hrs. 

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 10/20

  10 hrs. 

27. Low pass filter with cut off frequency of 100 kHz and high pass filter with cut off frequency of 50 kHz are connected in tandem, the resultant filter is

  Low pass filter with cut off frequency of 100 kHz   High pass filter with cut off frequency of 50 kHz   Band pass filter with pass band from 50 kHz to 100 kHz.   None of the above. 

28. In case of oil fire, the fire extinguisher used is

  Soda Acid   Foam   Carbon dioxide   Carbon Tetra chloride

29. The output of a 2-input NAND gate with high at both the inputs will be

  High   Low   High & low   None of the above. 

30. The input impedance of an op-amp is

  High   Low 

  Medium   None of the above

Answers 

1(a), 2 (d), 3 (a), 4 (c), 5 (c) 6 (a) 7 (b) 8 (a) 9 (a) 10 (c) 11 (d) 12 (c) 13 (a) 14 (a) 15 (a)

16 (c) 17 (b) 18 (c) 19 (a) 20 (d) 21 (c) 22 (b) 23 (b) 24 (a) 25 (a) 26 (b) 27 (c) 28 (b) 29 (b)30 (a).

 

1. The velocity of sound is the least in which of the following medium:1) Air 2) Water 3) Wood 4) Vacuum

2. Two amplifier stages have voltage gains of 100 and 200. The total decibel voltage gain

of the cascaded amplifiers is:1) 46 dB 2) 86 dB 3) 66 dB 4) 106 dB

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 11/20

3. In the circuit shown, what is the minimum value of RL for which the output voltage willremain constant?

2

1. Voltage across 4 ohm resistance in respect of the following drawing circuit

will be

a) 12 V b) 6 Vc) 4 V d) 20 V

2. One unit of consumption in electrical installation is equal to

a) 1 ampere b) 1 watt hour 

c) 1 kilowatt hour d) 1 volt ampere

3. Power rating of component is expressed in

a) Ampere b) Voltagec) Watt d) Ampere hour 

4. In a diesel engine, governor controls

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 12/20

a) Load current b) Output voltage of an alternator 

c) Freq. of the generating voltage d) None of the above

5. In a domestic electrical wiring various lamps are connected in

a) Parallel b) Seriesc) Some in series and some in parallel d) None of the above

6. Instrument used for measuring the rotational speed of an engine is

a) Speedometer b) Anemometer c) Tachometer d) All the above

7. 8000 micro farad is same as

a) 8 x 10-6 farad b) 8 x 10-9 faradc) 8 x 10-3 farad d) 8 x 106 farad

8. In a sinusoidal wave, peak voltage is equal to

a) RMS voltage b) RMS Voltage ¸ Ö2c) Ö2 RMS voltage d) 1.1 RMS voltage

9. Farad is the unit of 

a) Inductance b) Capacitancec) Resistance d) None of the above

10. LP/HP cut out is used in

a) Diesel Generator b) AC plantsc) Air flow meter d) watt hour meter 

11. A megger is an instrument used for measuring

a) Very high voltage b) Very low voltage

c) Very high current d) Very high resistance

12. Star-Delta starter can be used in

a) 2HP 230 volt AC motor b) 5 HP 400 volt AC motor c) 5 HP DC motor d) None of the above

13. The speed of an 8- pole alternator to generate 400 v at 50 Hz will be

a) 750 rpm b) 900 rpmc) 1500 rpm d) 450 rpm

14. The value of the resistance having coloured strips as shown in figure is

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 13/20

 

a) 2200 + 10% b) 2200 + 5%c) 470 ohm d) 2000 + 10%

15. In a condenser of an air conditioning plant heat is transferred from

a) water to air b) refrigerant to water c) air to water d) water to refrigerant

17. In three phase connection, phase current is

a) Equal to line current b) less than line currentc) Greater than line current d) cannot be predicted

18. If fire takes place in air circuit breaker, the fire extinguisher used will be

a) Foam type b) CO2 typec) Water d) Sand

19. Electrical energy is converted into mechanical energy by

a) Solar Cell b) Steam Enginec) AC/DC motor d) Solar Cooker 

20 Loudspeaker converts

a) Sound into electrical energy b) Electrical energy into soundc) Light into electrical energy d) Heat into electrical energy

21. _________________ amplifier is used immediately after microphone

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 14/20

1. Three 100W non-inductive resistors, when connected in star across 400 V, 50 Hz, 3 phaseconsumes 1600 W. When one of the resistances becomes open, the power consumption isreduced by:

a) half b) one third c) two third d) one fourth

2. The power input to a three phase induction motor is 62 kW. The stator loss is 2 kW. If therotor is running with a slip of 5%, the total copper loss in the rotor will be:

a) 500 W b) 1000 W c) 1500 W d) 3000 W

3. A transformer has an iron loss of 250 W and full-load copper loss of 1000 W. At what percentage of full-load, the efficiency becomes maximum:

a) 70% b) 66% c) 50% d) 25%

4. Operational amplifier can amplify:

a) AC signals only b) DC signals onlyc) Both AC and DC signals d) All of the above

5. Adjacent channel rejection of a receiver is determined by its:

a) Fidelity b) Noise figure c) Selectivity d) Sensitivity

6. In a three input NAND gate, one input is low. The output will be:

a) Low b) Will depend upon other two inputsc) High d) None of the above

7. If the conduction in the anode circuit takes place for less than 180o of the input cycle, theamplifier is classified as:

a) Class A b) Class B c) Class C d) Super Class

8. 500 MHz falls in the;

a) HF Band b) VHF Bandc) UHF Band d) SHF Band

9. The signals sent by the TV transmitter to ensure correct scanning in the receiver are called:

a) Sync b) Chroma c) Luminance d) Video

10. A frequency modulated signal, which is modulated by a 3 kHz sine wave swings between100.02 MHz and 99.98 MHz. The modulation index of the signal will be:

a) 20/3 b) 40/3 c) 10/3 d) 5/3

ANSWERS 1. A 2. D 3. C 4. D 5. C 6. C 7. D 8. C 9. C 10. A

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 15/20

 

1 Which of the following is not true for common collector amplifier?

 

o  It offers high input impedance. b) It offers low output impedance.

o  It offers wide band width. d) It offers a large gain.

2. Which of the following is not true with respect to negative feedback?

 

o  It increases gain. b) It improves distortion.

c) It improves signal to noise ratio. d) It improves bandwidth.

3.If the conduction in the anode circuit takes place for less than 180o of the input cycle, theamplifier is classified as:

a) Class A b) Class B c) Class C d) Class D

4. The following network will act as a

a) Low pass filter b) High pass filter c) Band pass filter d) Band stop filter 

5. In Satellite Broadcasting, the down link frequency in C band range is

a) 2.5 GHz to 2.7 GHz b) 3.7 GHz to 4.2 GHzc) 4.5 GHz to 4.8 GHz d) 11.7 GHz to 12.2 GHz

6. In a 100 kW AM transmitter, if the carrier is modulated with 100% modulation index, power in the lower side band will be:

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 16/20

a) 100 kW b) 50 kW c) 25 kW d) 12.5 kW

7. The ratio of reflected power to incident power is

a) Reflection Co-efficient b) (Reflection Co-efficient)2c) VSWR d) (VSWR)2

8. The equation relating VSWR with reflection coefficient is

a) b)

c) d)

9. The amount of pre-emphasis given to the audio signal in AIR in FM broadcasting is

a) 25 msec. b) 50 m sec c) 75 m sec. d) 100 m sec.

10. The characteristic impedance of free space is

a) 50 ohms b) 120 ohm c) 377 ohms d) 440 ohms

11. Which of the following is not expressed in watt?

a) V2/R b) I2R c) VxI d) V/I

12. 4 mF is same as

a) 0.004 nF b) 40 nF c) 400 nF d) 4000 nF

13. An electronic fan regulator 

a) is a current divider b) voltage divider 

c) varies angle of conduction of ac wave d) None of the above

14 An ammeter has 1 A range and has a resistance of 10 W. To measure 10 A current withthis meter, we shall use a resistance

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 17/20

 

 

o  more than 10 ohms in series b) less than 10 ohms in series

c) more than 10 ohms in parallel d) less than 10 ohms in parallel

15. Which of the following acts as an open circuit to d.c?

a) Diode b) Inductor c) Capacitor d) All the above

Answers: 

1  2 3 4 5 6 7 8 9 10 11 12 13 14 15

d a c b c c b b b c d d c d c

 . Fill in the blanks:

  Secondary of a current transformer should never be ____________.

   ____________.  The equipment required for maintenance of a wet battery is ____________.

  All electrical installations should be tested for good insulation at least once every

 __________.

  Stock of Carbon Tetrachloride should be maintained in ______________ register.

  The refrigerant in an a.c. plant gets converted from gaseous state to liquid state in the

 ____________.

  When a circuit breaker is drawn out of the rack, the connection spout shutters should be

 ____________.

  …………………………….. 

  A scientific tool for monitoring the progress of a Project is ____________.

  Spurious power emitted by transmitters can be judged with the help of a ____________.

Answers: 

1. Open Circuited 2. ………………… 3. Hydrometer 4. Six months 5. S150 6. Condensor 7. ………………… 8. 48 9. PERT Chart10. Spectrum Analyzer 

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 18/20

Multiple choice Questions

1. The velocity of sound is the least in which of the following medium:1) Air 2) Water 3) Wood 4) Vacuum

2. Two amplifier stages have voltage gains of 100 and 200. The total decibel voltage gainof the cascaded amplifiers is:

1) 46 dB 2) 86 dB 3) 66 dB 4) 106 dB

3. In the circuit shown, what is the minimum value of RL for which the output voltage willremain constant?

1) 15 W 2) 24 W 3) 27 W 4) 45 W

4 If 1/10th of the total current is to pass through a galvanometer of resistance G W, then theshunt resistance should be:

1) G/99 W 2) G/9 W 3) G/10 W 4) Gx9 W

5

In the circuit shown, each condenser has a capacitance of 1mF. The equivalentcapacitance between P and Q is:1) 3 mF 2) 6 mF 3) 1 mF 4) 1/3 mF

6. In an electric circuit, the applied voltage is E=100 Sin (314t) V and the resultant current is

I = 5 Sin (314t + p/3). Then, the circuit is comprised of:1) L and C 2) L only 3) R and C 4) R and L

7 At any frequency much higher than the resonant frequency of a series resonance circuit,the angle of impedance Z approaches:

1) -90° 2) +90° 3) 0° 4) 180°

8. An indirectly heated pentode has how many pins?1) 5 2) 6 3) 7 4) 8

9 The binary number that follows 0110 1111 is:1) 0110 1100 2) 0111 0000 3) 0111 1000 4) 0110 1110

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 19/20

10. A transformer has an iron loss of 300 W and full load copper loss of 1200 W. At what percentage of full load does the efficiency become maximum?

1) 80% 2) 60% 3) 50% 4) 25%

11 In a three phase, four wire circuit, the line currents in the R, Y and B phases are 1, 2 and 1

A respectively. What is the current in the neutral conductor?1) 1 A 2) 2 A 3) 3 A 4) 4 A

12 A FM transmitter operating at 104 MHz is modulated with 5 kHz tone and the maximumdeviation is 75 kHz. Total bandwidth occupied by the FM transmitter will be:

1) 150 kHz 2) 160 kHz 3) 170 kHz 4) None of these

13. What is the aspect ratio in conventional Television?1) 2:1 2) 3:2 3) 4:3 4) 5:4

14 What is the type of modulation adopted for the Chrominance signal in TV?

1) Amplitude modulation 2) Frequency modulation3) Phase modulation 4) Quadrature Amplitude modulation

15. A 10 kW transmitter is connected to an antenna and the reflection coefficient observedon the transmission line is 0.6. The power radiated by the antenna is:

1) 10 kW 2) 3.6 kW 3) 6.4 kW 4) None of these

16. Transmission in short wave is characterised by the following:1) It takes place by sky wave. 2) Propagation is by reflection from ionosphere.3) It is subject to severe fading. 4) All of these.

17. Reception of a signal through direct wave depends upon the following:1) Height of the transmitting antenna 2) Height of the receiving antenna3) Distance between the transmitter and receiver 4) All the above

18. Which of the following diodes exhibits negative resistance phenomenon?1) Zener Diode 2) Ordinary Diode 3) Tunnel Diode 4) PIN Diode

19. Which has the longest wave length?1) Microwave 2) X-ray 3) Ultraviolet ray 4) Infrared ray

20. An infinite line of characteristic impedance Zo is terminated by an impedance ZL. Whatis its input impedance?1) Infinity 2) Zo 3) ZL 4) (Zo.ZL)1/2

Answers of the above problems : 

Q.No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20Ans. 4 2 4 2 1 3 2 3 2 3 1 2 3 4 3 4 4 3 1 2

7/28/2019 ece_mcq

http://slidepdf.com/reader/full/ecemcq 20/20

 l