Semiconductor Electronics: Materials, Devices and Simple Circuits MCQ Questions for Class 12 Physics Chapter 14 with Answers

Find here the NCERT chapter-wise Multiple Choice Questions from Class 12 Physics book Chapter 14 Semiconductor Electronics: Materials, Devices and Simple Circuits with Answers Pdf free download. This may assist you to understand and check your knowledge about the chapters. Students also can take a free test of the Multiple Choice Questions of Semiconductor Electronics: Materials, Devices and Simple Circuits. Each question has four options followed by the right answer. These MCQ Questions are selected supported by the newest exam pattern as announced by CBSE.

NCERT MCQ Chapters for Class 12 Physics

Q1. What happens during regulation action of a Zener diode?

(i) The current through the series resistance (Rs) changes.
(ii) The resistance offered by the Zener changes.
(iii) The Zener resistance is constant.
(iv) Both (i) and (ii)

(iv) Both (i) and (ii)

Q2. In a p-type semiconductor, current conduction is by:

(i) atoms
(ii) holes
(iii) electrons
(iv) protons

(ii) holes

Q3. To reduce the ripples in a rectifier circuit with capacitor filter which one is false?

(i) RL should be increased.
(ii) Input frequency should be decreased.
(iii) Input frequency should be increased.
(iv) Capacitors with high capacitance should be used.

(ii) Input frequency should be decreased.

Q4. Electric conduction in a semiconductor takes place due to

(i) electrons only
(ii) holes only
(iii) both electrons and holes
(iv) neither electrons nor holes

(iii) both electrons and holes

Q5. The energy band gap is maximum in which of the following?

(i) Metals
(ii) Superconductors
(iii) Insulators
(iv) Semiconductors

(iii) Insulators

Q6. If a small amount of antimony is added to germanium crystal

(i) it becomes a p–type semiconductor
(ii) the antimony becomes an acceptor atom
(iii) there will be more free electrons than holes in the semiconductor
(iv) its resistance is increased

(iii) there will be more free electrons than holes in the semiconductor

Q7. Potential barrier developed in a junction diode opposes the flow of

(i) minority carrier in both regions only
(ii) majority carriers only
(iii) electrons in p region
(iv) holes in p region

(ii) majority carriers only

Q8. With fall of temperature, the forbidden energy gap of a semiconductor

(i) increases
(ii) decreases
(iii) sometimes increases and sometimes decreases
(iv) remains unchanged

(iv) remains unchanged

Q9. For the depletion region of a diode which one is incorrect?

(i) There are no mobile charges.
(ii) Equal number of holes and electrons exists, making the region neutral.
(iii) Recombination of holes and electrons has taken place.
(iv) Immobile charged ions exist.

(i) There are no mobile charges.

Q10. A p-type semiconductor is

(i) positively charged
(ii) negatively charged
(iii) uncharged
(iv) uncharged at 0K but charged at higher temperatures

(iii) uncharged

Q11. At absolute zero, Si acts as which of the following?

(i) Non-metal
(ii) Metal
(iii) Insulator
(iv) Superconductor

(iii) Insulator

Q12. The electrical conductivity of pure germanium can be increased by

(i) increasing the temperature
(ii) doping acceptor impurities
(iii) doping donor impurities
(iv) All of the above

(iv) All of the above

Q13. Region without free electrons and holes in a p-n junction is

(i) n-region
(ii) p-region
(iii) depletion region
(iv) none of these

(iii) depletion region

Q14. Number of electrons in the valence shell of a semiconductor is:

(i) 1
(ii) 2
(iii) 3
(iv) 4

(iv) 4

Q15. In a p-n junction diode, change in temperature due to heating:

(i) affects only reverse resistance
(ii) affects only forward resistance
(iii) Does not affect resistance of p-n junction
(iv) affects the overall V-I characteristics of p-n junction

(iv) affects the overall V-I characteristics of p-n junction

Q16. In a semiconductor

(i) there are no free electrons at 0 K
(ii) there are no free electrons at any temperature
(iii) the number of free electrons increases with pressure
(iv) the number of free electrons is more than that in a conductor

(i) there are no free electrons at 0 K

Q17. Which of the following is true regarding insulators?

(i) The valence band is partially filled with electrons
(ii) The conduction band is partially filled with electrons
(iii) The conduction band is filled with electrons and valence band empty
(iv) The conduction band is empty and valence band is filled with electrons

(i) The valence band is partially filled with electrons

Q18. The gate for which output is high if atleast one input is low?

(i) NAND
(ii) NOR
(iii) AND
(iv) OR

(iv) OR

Q19. In a half wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be

(i) 25 Hz
(ii) 50 Hz
(iii) 70.7 Hz
(iv) 100 Hz

(ii) 50 Hz

Q20. Bonds in a semiconductor :

(i) trivalent
(ii) covalent
(iii) bivalent
(iv) monovalent

(ii) covalent

Q21. In a semiconductor, the forbidden energy gap between the valence band and the conduction band is of the order is

(i) 1 MeV
(ii) 0.1 Mev
(iii) 1 eV
(iv) 5 eV

(iii) 1 eV

Q22. Let nh and ne be the number of holes and conduction electrons in an extrinsic semiconductor. Then

(i) nh > ne
(ii) nh = ne
(iii) nh < ne
(iv) nh ≠ ne

(iv) nh ≠ ne

Q23. If the energy of a photon of sodium light (A = 589 nm) equals the band gap of semiconductor, the minimum energy required to create hole electron pair

(i) 1.1 eV
(ii) 2.1 eV
(iii) 3.2 eV
(iv) 1.5 eV

(ii) 2.1 eV

Q24. In reverse biasing:

(i) large amount of current flows
(ii) no current flows
(iii) potential barrier across junction increases
(iv) depletion layer resistance increases

(iii) potential barrier across junction increases

Q25. Temperature coefficient of resistance of semiconductor is

(i) zero
(ii) constant
(iii) positive
(iv) negative

(iv) negative

Q26. Which of the following is an amorphous solid?

(i) Glass
(ii) Diamond
(iii) Salt
(iv) Sugar

(i) Glass

Q27. The impurity atoms with which pure silicon may be doped to make it a p-type semiconductor are those of

(i) phosphorus
(ii) boron
(iii) antimony
(iv) nitrogen

(ii) boron

Q28. If in a n-type semiconductor when all donor states are filled, then the net charge density in the donor states becomes

(i) 1
(ii) > 1
(iii) < 1, but not zero
(iv) zero

(ii) > 1

Q29. Main function of a transistor is to :

(i) rectify
(ii) simplify
(iii) amplify
(iv) all the above

(iii) amplify

Q30. In an n-type semiconductor, donor valence band is

(i) above the conduction band of the host crystal
(ii) close to the valence band of the host crystal
(iii) close to the conduction band of the host crystal
(iv) below the valence band of the host crystal

(iii) close to the conduction band of the host crystal

Q31. At which temperature, a pure semiconductor behaves slightly as a conductor?

(i) Low temperature
(ii) Room temperature
(iii) High temperature
(iv) Supercritical temperature

(iii) High temperature

Q32. What is the resistivity of a pure semiconductor at absolute zero ?

(i) Zero
(ii) Infinity
(iii) Same as that of conductors at room temperature
(iv) Same as that of insulators at room temperature

(ii) Infinity

Q33. At absolute zero, Si acts as a

(i) metal
(ii) semiconductor
(iii) insulator
(iv) none of these

(iii) insulator

Q34. To obtain electrons as majority charge carriers in a semiconductors the impurity mixed is:

(i) monovalent
(ii) divalent
(iii) trivalent
(iv) pentavalent

(ii) divalent

Q35. Diffusion current in a p-n junction is greater than the drift
current in magnitude

(i) if the junction is forward-biased
(ii) if the junction is reverse-biased
(iii) if the junction is unbiased
(iv) in no case

(i) if the junction is forward-biased

Q36. What is a rectifier used for?

(i) Convert ac voltage to dc voltage
(ii) Convert dc voltage to ac voltage
(iii) Measure resistance
(iv) Measure current

(i) Convert ac voltage to dc voltage

Q37. A semiconductor device is connected in a series circuit with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops to almost zero. The device may be a/an

(i) intrinsic semiconductor
(ii) p-type semiconductor
(iii) n-type semiconductor
(iv) p-n junction diode

(iv) p-n junction diode

Q38. In good conducrors of electricity the type of bonding that exist is

(i) Van der Walls
(ii) covalent
(iii) ionic
(iv) metallic

(iv) metallic

Q39. In a common base amplifier the phase difference between the input signal voltage and output voltage is :

(i) π/2
(ii) 0
(iii) π/4
(iv) π

(ii) 0

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