ELECTRICIAN 2nd YEAR MODULE – Electronic Practice ONLINE TEST

Question 1 of 69

1. Which resistor is used to measure light intensity?

PTC

VDR

LDR

NTC

Question 1 of 69

Question 2 of 69

2. Why is negative feedback required in amplifier circuits?

To increase the output voltage gain

To increase the output current gain

To increase the amplification factor

To reduce the distortion

Question 2 of 69

Question 3 of 69

3. What is the effect of pinch-off voltage in JFET?

Reverse bias voltage becomes zero

Width of channel has maximum value

Drain current becomes zero

No depletion region exists

Question 3 of 69

Question 4 of 69

4. What is the type of amplifier circuit?

Class B push pull amplifier

Common base amplifier

Common emitter amplifier

Common collector amplifier

Question 4 of 69

Question 5 of 69

5. What is the reason for widened barrier in a reverse biased diode?

Holes in P material attracted to negative terminal

Electrons and holes are attracted towards supply terminals

Minority carriers in two materials are neutralized

Electron in N material is drifted to positive terminal

Question 5 of 69

Question 6 of 69

6. What is the main advantage of a class A amplifier?

Minimum signal to noise ratio losses

Maximum voltage gain

Minimum distortion

Maximum current gain

Question 6 of 69

Question 7 of 69

7. Why is a snubber circuit used in the TRIAC motor control circuit?

To increase the motor torque

To avoid false triggering

To maintain the motor speed constant

To increase the life of TRIAC

Question 7 of 69

Question 8 of 69

8. What is the name of this logic gate symbol? [Two input logic gate]

Two input NOR gate

Two input OR gate

Two input NAND gate

Two input AND gate

Question 8 of 69

Question 9 of 69

9. What is the characteristic property of base material in a transistor?

Lightly doped and very thin

Heavily doped and very larger

Heavily doped and very thin

Lightly doped and very larger

Question 9 of 69

Question 10 of 69

10. How can the input impedance of CRO be increased?

By increasing time/base attenuator switch position

By adding resistance to trigger level circuit

By increasing volts/cm attenuator switch position

By adding resistance to CRO probe

Question 10 of 69

Question 11 of 69

11. Why are most semiconductor devices made from silicon compared to germanium?

High resistance range

High barrier voltage

High thermal conductivity

High current carrying capacity

Question 11 of 69

Question 12 of 69

12. What is the main application of uni junction transistor?

Amplification

Triggering circuits

Rectification

Regulator circuits

Question 12 of 69

Question 13 of 69

13. What is the main function of Uni Junction Transistor (UJT)?

Broadcast transmitter

Relaxation oscillator

Loud speaker amplifier

Microphone input device

Question 13 of 69

Question 14 of 69

14. Which resistor determines the voltage gain in a common emitter amplifier?

Re

R2

RL

R1

Question 14 of 69

Question 15 of 69

15. What is the power gain of CE amplifier with a voltage gain of 66 and β (Beta) of the transistor is 100?

166

6600

0.66

1.5

Question 15 of 69

Question 16 of 69

16. How does the depletion region behave?

As semiconductor

As insulator

As conductor

As resistor

Question 16 of 69

Question 17 of 69

17. Which is the advanced version of power electronic component used in the output stage in drives?

UJT

IGBT

FET

SCR

Question 17 of 69

Question 18 of 69

18. What is the difference in current control of MOSFET compared to JFETs?

Insulating layer instead of junction

Using N material gate instead of P material

Using N material instead of P material

Using P material instead of N material

Question 18 of 69

Question 19 of 69

19. Which filter circuit is capable of removing voltage spikes in the rectifier circuit?

RC filter

Series inductor filter

LC filter

Capacitor input filter

Question 19 of 69

Question 20 of 69

20. What determines whether a material is a conductor, semiconductor or insulator?

Existence of valence electrons in atom

Atomic bonding structure of atom

Atomic weight of the atom of the material

Atomic number of the atom of the material

Question 20 of 69

Question 21 of 69

21. Which logic gate's operation is represented by this truth table?

NOT gate

NOR gate

OR gate

AND gate

Question 21 of 69

Question 22 of 69

22. What is the output voltage in the full wave rectifier circuit?

Double the rated output

Half the rated output

Rated output

No output

Question 22 of 69

Question 23 of 69

23. What is the purpose of using Binary Coded Decimal (BCD) system in digital circuits?

Interface to binary system

Segregating the input parameters

Control the binary system

Storing the data inputs

Question 23 of 69

Question 24 of 69

24. Why is a feedback network used in the oscillator?

To cancel second harmonic distortion

To phase shift the signal by 60°

To phase shift the signal by 180°

To cancel noise distortion

Question 24 of 69

Question 25 of 69

25. What is the minimum and maximum value of a resistor with color bands: red, violet, orange, and gold?

22400Ω - 33600Ω

25650Ω - 28350Ω

24700Ω - 27300Ω

23750Ω - 26250Ω

Question 25 of 69

Question 26 of 69

26. Which device has very high input impedance, low noise output, good linearity and low inter-electrode capacity?

Field effect transistor

PNP transistor

NPN transistor

Uni junction transistor

Question 26 of 69

Question 27 of 69

27. What is the effect if SCR is latched into conduction and gate current is removed in DC?

Gate loses control over conduction

SCR gets cut off

Output voltage will be reduced

Current through SCR OFF

Question 27 of 69

Question 28 of 69

28. How many characters are in hexadecimal number system?

12

16

6

8

Question 28 of 69

Question 29 of 69

29. Which electronic circuit produces signal waves or pulses without an input?

Oscillator

Amplifier

Detector

Modulator

Question 29 of 69

Question 30 of 69

30. What is the name of this amplifier?

Common collector amplifier

Class AB push pull amplifier

Common emitter amplifier

Class B push pull amplifier

Question 30 of 69

Question 31 of 69

31. Which oscillator provides highly accurate stable frequency?

Hartley oscillator

Colpitts oscillator

Quartz crystal oscillator

R.C phase shift oscillator

Question 31 of 69

Question 32 of 69

32. Which multivibrator produces a repetitive pulse wave form output?

Bistable multivibrator

Astable multivibrator

One shot multivibrator

Monostable multivibrator

Question 32 of 69

Question 33 of 69

33. How can a decimal number be converted into binary number?

Dividing decimal by 2

Multiplying decimal by 2

Multiplying decimal by 4

Divide decimal by 4

Question 33 of 69

Question 34 of 69

34. What is the name of this three-terminal electronic device symbol?

TRIAC

IGBT

SCR

DIAC

Question 34 of 69

Question 35 of 69

35. What is the main application of a Field Effect Transistor (FET)?

Low input impedance device

Current control device

Positive feedback device

Voltage control device

Question 35 of 69

Question 36 of 69

36. What is the main application of SCR (Silicon Controlled Rectifier)?

Speed control of motors

Amplifier

Oscillators

Multi vibrators

Question 36 of 69

Question 37 of 69

37. What is the primary function of this transistor circuit?

Switching

Amplification

Modulation

Oscillation

Question 37 of 69

Question 38 of 69

38. Which circuit is essential to maintain oscillations in an oscillator circuit?

Voltage multiplier

Negative feedback

Rectifier with filter

Positive feedback

Question 38 of 69

Question 39 of 69

39. How is the gate terminal of N-channel JFET biased?

Gates are reverse biased

Gates are forward biased with drain

Gates are forward biased

Gates are reverse biased with source

Question 39 of 69

Question 40 of 69

40. Which quantity can be measured by CRO (Cathode Ray Oscilloscope)?

Inductance

Power factor

Frequency

Resistance

Question 40 of 69

Question 41 of 69

41. Why is the collector region physically made larger than emitter region in a transistor?

It has to dissipate more heat

Base collector region is reverse biased

Collector region always operate with high voltage

Output taken from collector terminal

Question 41 of 69

Question 42 of 69

42. What is the purpose of connecting L1 through C1 to the transistor base?

Provides transistor biasing voltage

Provides DC supply

Provides negative feedback

Provides positive feedback

Question 42 of 69

Question 43 of 69

43. What is the type of amplifier?

Common Emitter Amplifier

Push Pull Amplifier

Common Base Amplifier

Emitter Follower Amplifier

Question 43 of 69

Question 44 of 69

44. Which electronic circuit generates AC signal without input?

Filter circuit

Rectifier circuit

Oscillator circuit

Amplifier circuit

Question 44 of 69

Question 45 of 69

45. Which type of control device is used in electronic fan regulator control circuits?

DIAC

TRIAC

UJT

FET

Question 45 of 69

Question 46 of 69

46. Which is a passive component?

Transistor

Diode

Capacitor

Diac

Question 46 of 69

Question 47 of 69

47. What is the output voltage if the center tap of transformer is open circuited in a full wave rectifier circuit?

Full rated output

Zero voltage

Half of the rated output

One fourth of rated output

Question 47 of 69

Question 48 of 69

48. Which device is made up of using the methods of point contact, grown, diffusion and alloy junctions?

Resistor

Capacitor

Transistor

Inductor

Question 48 of 69

Question 49 of 69

49. Which instrument provides a visual representation of measured quantities?

Cathode ray oscilloscope

Voltage stabilizer

Function generator

Radio frequency generator

Question 49 of 69

Question 50 of 69

50. What is the frequency of the displayed signal on CRO screen covered by 5 divisions with a time base setting of 0.2 microseconds?

10.0 KHz

1.0 KHz

100.0 KHz

1000.0 KHz

Question 50 of 69

Question 51 of 69

51. What defect will occur in the radio if the pulsations are not removed from the input of the rectifier?

Humming sound

No response

Works with low volume

Improper tuning

Question 51 of 69

Question 52 of 69

52. What is the use of time-base control switch or knob in the CRO?

Select sweep speed

Select intensity of the beam

Select input voltage range

Select input signal voltage

Question 52 of 69

Question 53 of 69

53. Which is an active component?

Capacitor

Inductor

Transistor

Resistor

Question 53 of 69

Question 54 of 69

54. Which logic gate's operation is represented by this truth table?

AND

NOT

NOR

NAND

Question 54 of 69

Question 55 of 69

55. What is the peak voltage of 220V RMS AC voltage?

315.20 V

311.17 V

312.25 V

310.02 V

Question 55 of 69

Question 56 of 69

56. Which doping material is used to make P-type semiconductor?

Boron

Phosphorous

Antimony

Arsenic

Question 56 of 69

Question 57 of 69

57. What is the output DC voltage in half wave rectifier, if the input AC voltage is 24 volt?

12 Volt

10.8 Volt

9.6 Volt

24 Volt

Question 57 of 69

Question 58 of 69

58. Which biasing is required for an NPN transistor to function as an amplifier?

Base positive, emitter negative and collector positive

Base positive, emitter negative and collector negative

Base ground, emitter and collector positive

Base negative, emitter positive and collector negative

Question 58 of 69

Question 59 of 69

59. What is the function of a transistor if emitter to base and collector to base are forward biased?

Acts as a closed switch

Acts as an oscillator

Acts as an amplifier

Acts as an open circuit

Question 59 of 69

Question 60 of 69

60. What is the function of R1 variable resistor in a TRIAC circuit?

Controls the pulse rate for triggering the TRIAC

Protects the RFI filter from overloading

Controls the current in R2

Protects from overload to TRIAC

Question 60 of 69

Question 61 of 69

61. What is the total turn-on time (t_ton) while transistor makes a transition from V₂ to V₁?

(t_ton)= t_d + t_r

(t_ton)= t_r - t_s

(t_ton)=  t_r -  t_d

(t_ton)= t_r+ t_d+ t_s

Question 61 of 69

Question 62 of 69

62. Which code indicates silicon semiconductor diode?

IN 4007

OA 79

BY 126

2N 3055

Question 62 of 69

Question 63 of 69

63. Which quadrant operation of SCR delivers heavy current in reverse biasing?

Third quadrant

First quadrant

Second quadrant

Fourth quadrant

Question 63 of 69

Question 64 of 69

64. What is the minimum voltage required in the base-emitter junction to conduct a silicon transistor?

0.4 V - 0.5 V

0.2 V - 0.3 V

0.8 V - 0.9 V

0.6 V - 0.7 V

Question 64 of 69

Question 65 of 69

65. What is the purpose of DIAC in power control circuits?

For triggering

For amplification

As an oscillator

As rectifier

Question 65 of 69

Question 66 of 69

66. What is the formula to calculate the resonance frequency in an oscillator circuit?

f_in = 1/2π√LC

f_in = 1/√2πL/C

f_r = 1/2π√LC

f_in =1/(LC)√2π

Question 66 of 69

Question 67 of 69

67. Which letter indicates the compound material cadmium sulphide?

'R'

'B'

'C'

'A'

Question 67 of 69

Question 68 of 69

68. What is the reason for higher barrier voltage in silicon material?

Doping percentage is more

Resistance is very low

Lower atomic number

Valence electrons are two only

Question 68 of 69

Question 69 of 69

69. What is the input ripple frequency (F_in) of full wave rectifier?

F_in = F

F_in = ½ F

F_in = √2 F

F_in = 2Fin

Question 69 of 69