NCERT Class 12 Chapter 14 Physics Semiconductor Electronics MCQ

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1. In the given figure V0 is the potential barrier across a p-n junction, when no battery is cdnnected across the junction. [NCERT Exemplar] CBSE Class12 Physics Semiconductor Electronics

CBSE Class12 Physics Semiconductor Electronics

A. 1 and 3 both correspond to forward bias of junction.

B. 3 corresponds to forward bias of junction and 1 corresponds to reverse bias of junction.

C. 1 corresponds to forward bias and 3 corresponds to reverse bias of junction.

D. 3 and 1 both correspond to reverse bias of junction

2. What happens during regulation action of a Zener diode?

A. The current through the series resistance (Rs) changes.

B. The resistance offered by the Zener changes.

C. The Zener resistance is constant

D. Both (i) and (ii)

3. When a pure semiconductor is heated, its resistance

A. Goes down

B. Goes up

C. Remains the same.

D. None of the above

4. In figure given, assuming the diodes to be ideal [NCERT Exemplar] CBSE Class12 Physics Semiconductor Electronics (4Q)

A. D₁ is forward biased and D₂ is reverse biased and hence current flows from A to B.

B. D₂ is forward biased and D1 is reverse biased and hence no current flows from B to A and vice versa.

C. D₁ and D₂ are both forward biased and hence current flows from A to B.

D. D₁ and D_{2 are both reverse biased and hence no current flows from A to B and vice versa}

5. In a p-type semiconductor, current conduction is by:

A. atoms

B. holes

C. electrons

D. protons

6. What is the order of forbidden gap in the energy bands of silicon?

A. 3.1 eV

B. 0.1 eV

C. 2.1 eV

D. 1.1 eV

7. The output of the given circuit in figure is given below. [NCERT Exemplar] CBSE Class12 Physics Semiconductor Electronics (7Q)

A. would be zero at all times

B. would be like a half-wave rectifier with positive cycles in output.

C. would be like a half-wave rectifier with negative cycles in output.

D. would be like that of a full-wave rectifier.

8. To reduce the ripples in a rectifier circuit with capacitor filter which one is false?

A. RL should be increased

B. Input frequency should be decreased.

C. Input frequency should be increased.

D. Capacitors with high capacitance should be used.

9. The densities of electrons and holes in an extrinsic semiconductor are 8 x 10¹⁵ cm^-3 and 5 x 1012 cm^-3 respectively. The mobilities of electrons and holes are respectively 23 x 10³ cm³ / Vs and 10² cm³ / Vs. Which type of semiconductor is it?

A. p-type only

B. n-type only

C. either n or p type

D. both n and p type

10. Electrical conductivity of a semiconductor

A. decreases with the rise in its temperature.

B. increases with the rise in its temperature.

C. does not change with the rise in its temperature.

D. first increases and then decreases with the rise in its temperature

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11. Electric conduction in a semiconductor takes place due to

A. electrons only

B. holes only

C. both electrons and holes

D. neither electrons nor holes

12. A semiconductor is formed by

A. Covalent bonds

B. Electrovalent bonds

C. Coordinate bonds

D. None of above

13. The forbidden energy band gap in conductors, semiconductors and insulators are EG₁,EG₂ and EG₃ respectively. The relation among them is

A. EG₁ = EG₂ = EG₃

B. EG₁ < EG₂ < EG₃

C. EG₁ > EG₂ > EG₃

D. EG₁ < EG₂ > EG₃

14. The energy band gap is maximum in which of the following?

A. Metals

B. Superconductors

C. Insulators

D. Semiconductors

15. Arrange the materials in ascending order of energy band gaps

A. conductor, semiconductor, insulator

B. insulator, semiconductor, conductor

C. semiconductor, conductor, insulator

D. insulator, conductor, semiconductor

16. If a small amount of antimony is added to germanium crystal

A. it becomes a p–type semiconductor

B. the antimony becomes an acceptor atom

C. there will be more free electrons than holes in the semiconductor

D. its resistance is increased

17. In a semiconductor, current conduction is due

A. Only to holes.

B. Only to electrons

C. To holes and electrons

D. None of the above

18. A n-type semiconductor is

A. negatively charged.

B. positively charged.

C. neutral.

D. none of these

19. Potential barrier developed in a junction diode opposes the flow of

A. minority carrier in both regions only

B. majority carriers only

C. electrons in p region

D. holes in p region

20. Electrons moving like molecules of a gas exist in:

A. all solids

B. covalent solids

C. metallic solids

D. ionic solids

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21. In the half-wave rectifier circuit shown. Which one of the following waveforms is true for V_CD the output across C and D?

CBSE Class12 Physics Semiconductor Electronics (21Q)

CBSE Class12 Physics Semiconductor Electronics (21Q)

A. (a)

B. (b)

C. (c)

D. (d)

22. With fall of temperature, the forbidden energy gap of a semiconductor

A. increases

B. decreases

C. sometimes increases and sometimes decreases

D. remains unchanged

23. An n-type semiconductor is

A. Not charged at all

B. Positively charged

C. Electrically neutral

D. Negatively charged

24. A full-wave rectifier circuit along with the input and output voltages is shown in the figure The contribution to output voltage from diode 2 is

CBSE Class12 Physics Semiconductor Electronics (24Q)

CBSE Class12 Physics Semiconductor Electronics (24Q)

A. A, C

B. B, D

C. B, C

D. A, D

25. For the depletion region of a diode which one is incorrect?

A. There are no mobile charges

B. Equal number of holes and electrons exists, making the region neutral

C. Recombination of holes and electrons has taken place.

D. Immobile charged ions exist