Semiconductor Physics – Multiple Choice Questions and Answers

Question-1. During forward bias:
(A) Anode connects to p-side
(B) Anode connects to n-side
(C) Anode is grounded
(D) Cathode connects to p-side

Question-2. Who was nicknamed “The Mayor of Silicon Valley” and credited with the realization of the first integrated circuit or microchip.
(A) Robert Norton Noyce
(B) William Shockley
(C) H. Earle Vaughan
(D) Nicolaas Bloembergen

Question-3. Electron pair bonding occurs when atoms:
(A) share electrons
(B) share holes
(C) share protons
(D) share neutrons

Question-4. Semiconductor devices can have:
(A) directional resistance
(B) variable resistance
(C) sensitivity to heat and light
(D) all of the above

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Question-5. When a doped semiconductor has less free holes it is called:
(A) p-type
(B) n-type
(C) pn-junction
(D) pnp-transistor

Question-6. Elements near which region of periodic table are usually used as semiconductors:
(A) Alkali metals
(B) Alkali earth metals
(C) Metalloid Staircase
(D) Lanthanides

Question-7. A P-N junction diode offers least resistance when:
(A) is reversed biased
(B) is doped
(C) is forward biased
(D) has high barrier potential.

Question-8. When the reverse bias of P-N junction diode becomes large, breakdown occurs. This condition is called:
(A) Leakage
(B) Rupture
(C) Avalanche
(D) Percolation

Question-9. Normal diodes are not designed to operate in the breakdown region, but ____ diodes can reliably operate in this region.
(A) BJT – Bipolar Junction transistor.
(B) LED – Light emitting diode
(C) Zener Diode
(D) Schottky diode

Question-10. MOSFET stands for
(A) Metal-Oxide Semiconductor – Free Electron Transistor
(B) Metal-Oxide Silicon – Free Effect Transformer
(C) Metal On Silicon – Field Effect Transistor
(D) Metal On Silicon – Free Electron Transistor

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Question-11. Typical metals used in Schottsky Diodes, which has metal-semiconductor junctions are:
(A) Iron, Aluminium, Copper
(B) Copper, Sodium, Potassium
(C) Gold, Silver, Mercury
(D) Molybdenum, Platinum, Chromium

Question-12. LED emits light (electroluminescence) and the color of light is determined by:
(A) Forward Bias
(B) Reverse Bias
(C) Current flowing through it
(D) Energy band gap

Question-13. LEDs used in electronic devices for numeric readouts are in the form of:
(A) light-arrays
(B) matrix
(C) seven-segment displays
(D) pixels

Question-14. LED with infrared or red light are made with:
(A) zinc selenide (ZnSe)
(B) gallium (III) phosphide (GaP)
(C) indium gallium nitride (InGaN)
(D) gallium arsenide (GaAs)

Question-15. Pure Green LED is made with:
(A) zinc selenide (ZnSe)
(B) aluminium gallium arsenide (AlGaAs)
(C) indium gallium nitride (InGaN)
(D) gallium arsenide (GaAs)

Question-16. In p-type semiconductor the majority carriers are:
(A) electrons
(B) holes
(C) protons
(D) neutrons

Question-17. Electric conduction in intrinsic semiconductor is mainly due to:
(A) migration of holes
(B) migration of electrons
(C) both
(D) none

Question-18. The acceptor atom for Silicon semiconductor is:
(A) selenium
(B) tellurium
(C) phosphorus
(D) zinc

Question-19. The donor atom for Silicon semiconductor is:
(A) beryllium
(B) boron
(C) phosphorus
(D) zinc

Question-20. Depletion Region in a P-N junction is also called
(A) insulated region
(B) charge-less region
(C) neutral region
(D) space charge layer

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Question-21. Due to Forward Bias, the depletion region is:
(A) narrowed
(B) broadened
(C) eliminated
(D) unchanged

Question-22. Low current conducted under reverse bias and the large current under forward bias is an example of:
(A) amplification
(B) rectification
(C) oscillation
(D) dampening

Question-23. Diffusion of electrons and holes at P-N junction is opposed by
(A) Forward Bias potential
(B) Reverse bias potential
(C) contact potential
(D) breakdown voltage

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Question-24. A bipolar transistor has terminals labelled as:
(A) gate, collector and emitter
(B) base, source and drain
(C) gate, source and drain
(D) base, collector and emitter

Question-25. The band gap for diamond is:
(A) 0.67 eV
(B) 3.4 eV
(C) 7.26 eV
(D) 5.5 eV

Question-26. The band gap for germanium (Ge) is:
(A) 0.67 eV
(B) 3.4 eV
(C) 7.26 eV
(D) 5.5 eV

Question-27. The energy required to promote a valence electron to become a conduction electron is called
(A) valence band
(B) conduction band
(C) bandgap
(D) Fermi level

Question-28. In n-type semiconductor, the Fermi-level lies:
(A) close to conduction band
(B) close to valence band
(C) equidistant from conduction and valence band
(D) does not exists

Question-29. Semiconductor materials are small band-gap ____________
(A) conductors
(B) metals
(C) gases
(D) insulators

Question-30. Which one of the following is not a charge carrier:
(A) electrons
(B) ions
(C) holes
(D) gamma rays


Question-31. The process of adding controlled impurities to a semiconductor is known as:
(A) contamination
(B) alloying
(C) compounding
(D) doping

Question-32. A silicon crystal doped with ______ creates a p-type semiconductor whereas one doped with ______ results in an n-type semiconductor.
(A) boron, phosphorus
(B) indium, gallium
(C) phosphorus, arsenic
(D) antimony, bismuth

Question-33. In a p-type semiconductor, the dopant is:
(A) bivalent
(B) trivalent
(C) tetravalent
(D) pentavalent

Question-34. In an intrinsic semiconductor, the Fermi-level lies:
(A) close to conduction band
(B) close to valence band
(C) equidistant from conduction and valence band
(D) does not exists

Question-35. The dopant in an n-type semiconductor is called
(A) Acceptor
(B) Rejector
(C) Donor
(D) Receiver

Question-36. The V-I characteristics of a diode is
(A) straight line with low positive slope
(B) straight line with high positive slope
(C) straight line with high negative slope
(D) not a straight line

Question-37. Silicon atoms combine in an orderly fashion called:
(A) Crystal
(B) Covalent Bond
(C) Semiconductor
(D) Polymer

Question-38. Reverse biased P-N junction diode may break down due to Avalanche or due to:
(A) shorting
(B) grounding
(C) quantum tunneling
(D) rupturing

Question-39. In a full-wave rectifier, the ripple frequency is (x) times the frequency of applied voltage. The value of (x) is:
(A) 1
(B) 2
(C) 3
(D) 4

Question-40. Zener diode in a regulated power supply behaves like a _______ in a hydraulic circuit.
(A) venturi
(B) non-return value
(C) check-valve
(D) nozzle

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Question-41. Photo diode always operate in _____ mode
(A) unbiased
(B) forward biased
(C) reverse biased
(D) none of the above

Question-42. The photo current in a photo-diode depends on ______ of the incident light
(A) frequency
(B) wavelength
(C) intensity
(D) duration

Question-43. The intensity of light emitted by an LED depends on __________
(A) forward bias
(B) reverse bias
(C) band gap
(D) forward current

Question-44. The ratio of collector current to base current is called ____ ratio
(A) alpha
(B) beta
(C) gamma
(D) delta

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Question-45. The _____ group impurity elements which donate free electrons to the pure semiconductor crystal are called as donor impurities
(A) second
(B) third
(C) fourth
(D) fifth

Question-46. _______ is defined as the ratio of change in base-emitter voltage to change in base current at constant collector-emitter voltage.
(A) alpha ratio
(B) beta ratio
(C) AC input resistance
(D) Dynamic output resistance

Question-47. ______ is an electronic device which converts DC voltage to AC voltage of desired frequency without any external input voltage.
(A) transformer
(B) half-wave rectifier
(C) full-wave rectifier
(D) oscillator

Question-48. The relation between current ratios: α and β is:
(A) α = β / (1 + β)
(B) β = α / (1 + α)
(C) α = β / (1 – β)
(D) β = α / (1 – β)

Question-49. Number of free electrons in conduction band is equal to number of holes in valence band in _______ semiconductor
(A) n-type
(B) extrinsic
(C) intrinsic
(D) p-type

Question-50. Pure semiconductors which conduct electricity on heating are called ________ semiconductors
(A) n-type
(B) extrinsic
(C) intrinsic
(D) p-type

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Answers to MCQs:

1. (A) Anode connects to p-side
2. (A) Robert Norton Noyce
3. (A) share electrons
4. (D) all of the above
5. (B) n-type
6. (C) Metalloid Staircase
7. (C) is forward biased
8. (C) Avalanche
9. (C) Zener Diode
10. (C) Metal On Silicon - Field Effect Transistor
11. (D) Molybdenum, Platinum, Chromium
12. (D) Energy band gap
13. (C) seven-segment displays
14. (D) gallium arsenide (GaAs)
15. (C) indium gallium nitride (InGaN)
16. (B) holes
17. (C) both
18. (D) zinc
19. (C) phosphorus
20. (D) space charge layer
21. (A) narrowed
22. (B) rectification
23. (C) contact potential
24. (D) base, collector and emitter
25. (D) 5.5 eV
26. (A) 0.67 eV
27. (C) bandgap
28. (A) close to conduction band
29. (D) insulators
30. (D) gamma rays
31. (D) doping
32. (A) boron, phosphorus
33. (B) trivalent
34. (C) equidistant from conduction and valence band
35. (C) Donor
36. (D) not a straight line
37. (A) Crystal
38. (C) quantum tunneling
39. (B) 2
40. (C) check-valve
41. (C) reverse biased
42. (C) intensity
43. (D) forward current
44. (B) beta
45. (D) fifth
46. (C) AC input resistance
47. (D) oscillator
48. (A) α = β / (1 + β)
49. (C) intrinsic
50. (C) intrinsic

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