a. Buchholz relay b. Reverse power relay c. Differential relay d. Overload relay Answer: b
Ques 1. A semiconductor is formed by ……… bonds.
A. Covalent B. Electrovalent C. Co‐ordinate D. None of the above
Answer: a
Ques 2. A semiconductor has ………… temperature coefficient of resistance.
Semi‐conductors & Electronics:
a. Positive b. Zero c. Negative
d. None of the above
Answer: c
Ques 3. The most commonly used semiconductor is ………..
a. Germanium b. Silicon c. Carbon d. Sulphur
Answer: b
Ques 4. A semiconductor has generally ……… valence electrons.
a. 2 b. 3 c. 6 d. 4
Answer: d
Ques 5. A semi‐conductor in its purest form is called a. Pure semi‐conductor
b. Doped semi‐conductor c. Intrinsic semi‐conductor d. Extrinsic semi‐conductor Answer: c
Ques 6. An extrinsic semiconductor is a a. Doped semi‐conductor b. Pure semi‐conductor c. Good insulator d. Good conductor Answer: a
Ques 7. Silicon that has been doped with a trivalent impurity is called a. P type semi‐conductor
b. N type semi‐conductor c. Intrinsic semi‐conductor d. Extrinsic semi‐conductor
Answer: a
Ques 8. In an n type semi‐conductor, free electrons are called a. Minority carrier
b. Valence electrons c. Majority carriers d. Charge carriers Answer: c
Ques 9. In an n type semi‐conductor, holes are called a. Minority carriers
b. Majority carriers c. Protons
d. Charge carriers Answer: a
Ques 10. When temperature increases, barrier potential a. Remains same
b. Decreases c. Increases
d. Depends on semi‐conductor material Answer: b
Ques 11. When temperature of a pure semi‐conductor is increased, its resistance a. Decreases
b. Remains the same c. Increases
d. Cannot be estimated Answer: a
Ques 12. As a general rule………are found only in semi‐conductors a. Electrons
b. Resistance c. Holes
d. None of the above Answer: c
Ques 13. Pure semi‐conductor atoms contain how many valence electrons?
a. 1 b. 2 c. 4 d. 8 Answer: c
Ques 14. When a pentavalent impurity is added to a pure semiconductor, it becomes ………
a. An insulator
b. An intrinsic semiconductor
c. p‐type semiconductor d. n‐type semiconductor
Answer: d
Ques 15. An n‐type semiconductor is ………
a. Positively charged b. Negatively charged c. Electrically neutral d. None of the above
Answer: c
Ques 16. A trivalent impurity has ….. valence electrons
a. 4 b. 5 c. 6 d. 3
Answer: d
Ques 17. Addition of trivalent impurity to a semiconductor creates many ……..
a. Holes
b. Free electrons c. Valence electrons d. Bound electrons
Answer: a
Ques 18. A hole in a semiconductor is defined as ……….
a. A free electron
b. The incomplete part of an electron pair bond c. A free proton
d. A free neutron
Answer: b
Ques 19. In a semiconductor, current conduction is due to ……..
a. Only holes
b. Only free electrons c. Holes and free electrons d. None of the above
Answer: c
Ques 20. The battery connections required to forward bias a pn junction are ……
a. +ve terminal to p and –ve terminal to n b. ‐ve terminal to p and +ve terminal to n c. ‐ve terminal to p and –ve terminal to n d. None of the above
Answer: a
Ques 21. In the depletion region of a pn junction, there is a shortage of ……..
a. Acceptor ions b. Holes and electrons c. Donor ions
d. None of the above
Answer: b
Ques 22. A reverse bias pn junction has …………
a. Very narrow depletion layer b. Almost no current
c. Very low resistance d. Large current flow
Answer: b
Ques 23. Avalanche effect occurs at a. Higher reverse voltage b. Lower reverse voltage c. Higher forward voltage d. Lower forward voltage Answer: a
Ques 24. Avalanche breakdown in a semi‐conductor takes place a. When forward current exceeds a certain value b. When potential barrier is reduced to zero c. When reverse bias exceeds a certain value d. When forward bias exceeds a certain value Answer: c
Ques 25. The leakage current across a p‐n junction is due to …………..
a. Minority carriers b. Majority carriers c. Junction capacitance d. None of the above
Answer: b
Ques 26. With forward bias to a pn junction , the width of depletion layer ………
a. Decreases b.Increases
c. Remains the same d. None of the above
Answer: a
Ques 27. A zener diode has ………..
a. one pn junction b. two pn junctions c. three pn junctions d. none of the above
Answer: a
Ques 28. A zener diode is used as ……….
a. an amplifier b. a voltage regulator c. a rectifier
d. a multivibrator Answer: b
Ques 29. A zener diode is always ………… connected.
a. reverse b. forward
c. either reverse or forward d. none of the above
Answer: a
Ques 30. A zener diode utilizes ……….. characteristics for its operation.
a. forward b. reverse
c. both forward and reverse d. none of the above
Answer: b
Ques 31. In the breakdown region, a zener didoe behaves like a ……… source.
a. constant voltage b. constant current c. constant resistance d. none of the above
Answer: a
Ques 32. There is a need of transformer for ………..
a. half‐wave rectifier
b. centre‐tap full‐wave rectifier c. bridge full‐wave rectifier d. none of the above
Answer: b
Ques 33. The most widely used rectifier is ……….
a. half‐wave rectifier
b. centre‐tap full‐wave rectifier c. bridge full‐wave rectifier d. none of the above
Answer: c
Ques 34. For a full wave rectifier, the output frequency a. Equals one half the input frequency b. Equals the line frequency
c. Equals two times the input d. Is 3 times the line frequency Answer: c
Ques 35. The frequency of the half wave rectifier signal is a. Twice the line frequency
b. Equal to the line frequency c. One half of the line frequency d. One fourth of the line frequency Answer: b
Ques 36. The temperature coefficient of resistance of a semi‐conductor is a. Positive
b. Negative c. Zero d. Infinity Answer: b
Ques 37. At absolute zero temperature a semi‐conductor behaves a a. Good conductor
b. Super conductor c. Insulator
d. Variable resistor Answer: c
Ques 38. A transistor has ………
a. one pn junction b. two pn junctions c. three pn junctions d. four pn junctions
Answer: b
Ques 39. The number of depletion layers in a transistor is …………
a. four b. three c. one d. two
Answer: d
Ques 40. The element that has the biggest size in a transistor is ………..
a. collector b. base c. emitter
d. collector‐base‐junction
Answer: a
Ques 41. In a pnp transistor, the current carriers are ………….
a. acceptor ions b. donor ions c. free electrons d. holes
Answer: d
Ques 42. In a npn transistor, ………. are the minority carriers
a. free electrons b. holes
c. donor ions d. acceptor ions
Answer: b
Ques 43. In a transistor ………..
a. IC = IE + IB b. IB = IC + IE c. IE = IC – IB d. IE = IC + IB
Answer: d
Ques 44. The most commonly used transistor arrangement is ……… arrangement
a. common emitter b. common base c. common collector d. none of the above
Answer: a
Ques 45. A transistor is connected in CB mode. If it is not connected in CE mode with same bias voltages, the values of IE, IB and IC will …………..
a. remain the same b. increase
c. decrease
d. none of the above
Answer: a
Ques 46. The most commonly used semiconductor in the manufacture of a transistor is ………….
a. germanium b. silicon c. carbon
d. none of the above
Answer: b
Ques 47. The collector‐base junction in a transistor has ………..
a. forward bias at all times b. reverse bias at all times c. low resistance
d. none of the above
Answer: b
Ques 48. For proper operation of the transistor, its collector should have …………
a. Proper forward bias b. Proper reverse bias c. Very small size d. None of the above
Answer: b
Ques 49. If the value of collector current IC increases, then the value of VCE …………
a. Remains the same b. Decreases
c. Increases
d. None of the above
Answer: b
Ques 50. An SCR has ……….. pn junctions
a) Two b) Three c) Four
d) None of the above
Answer: b
Ques 51. An SCR has ………….. semiconductor layers
a) Two b) Three c) Four
d) None of the above
Answer: c
Ques 52. An SCR has three terminals viz ………
a) Cathode, anode, gate b) Anode, cathode, grid c) Anode, cathode, drain d) None of the above
Answer: a
Ques 53. An SCR behaves as a ………. Switch
a) Unidirectional b) Bidirectional c) Mechanical d) None of the above
Answer: a
Ques 54. An SCR is sometimes called …………
a) Triac b) Diac
c) Unijunction transistor d) Thyristor
Answer: d
Ques 55. In the normal operation of an SCR, anode is ……… w.r.t. cathode
a) At zero potential b) Negative
c) Positive
d) None of the above
Answer: c
Ques 56. In normal operation of an SCR, gate is ………..w.r.t. cathode a) Positive
b) Negative
c) At zero potential d) None of the above
Answer: a
Ques 57. The control element of an SCR is ………….
a) Cathode b) Anode c) Anode supply d) Gate
Answer: d
Ques 58. An SCR is turned off by ……….
a) Reducing anode voltage to zero b) Reducing gate voltage to zero c) Reverse biasing the gate d) None of the above
Answer: a
Ques 59. An SCR is a ……….. triggered device
a) Voltage b) Current
c) Voltage as well as current d) None of the above
Answer: b
Ques 60. An SCR is turned off when …………..
a) Anode current is reduced to zero b) Gate voltage is reduced to zero c) Gate is reverse biased
d) None of the above
Answer: a
Ques 61. If firing angle in an SCR circuit is increased, the output …………
a) Remains the same b) Is increased c) Is decreased d) None of the above
Answer: c
Ques 62. If gate current is increased, then anode‐cathode voltage at which SCR closes ……….
a) Is decreased b) Is increased c) Remains the same d) None of the above
Answer: a
Ques 63. When SCR is OFF, the current in the circuit is ……….
a) Exactly zero
b) Small leakage current c) Large leakage current d) None of the above
Answer: b
Ques 64. An SCR can exercise control over ………. of a.c. supply
a) Positive half‐cycles only b) Negative half‐cycles only
c) Both positive and negative half‐cycles d) Positive or negative half‐cycles
Answer: d
Ques 65. When SCR starts conducting, then ………. loses all control a) Gate
b) Cathode c) Anode
d) None of the above
Answer: a
Ques 66. A……….is considered a current controlled device a. Diode
b. Conductor c. Transistor d. Resistor Answer: c
Ques 67. A……….is considered as voltage controlled device a. FET
b. Diode c. Transistor d. Capacitor Answer: a
Ques 68. What semi‐conductor material is used in the construction of LED?
a. Silicon b. Germanium c. Gallium
d. Gallium arsenide Answer: d
Ques 69. In an amplifier the emitter junction is a. Forward biased
b. Reverse biased c. Grounded d. Shorted Answer: a