Physics Class 12 MCQ Semiconductor Electronics : Materials, Devices And Simple Circuits – Chapter 14

Ques 1: In Conductor, Semiconductor and Insulator, the forbidden energy gap are E₁, E₂ and E₃ respectively. Which one is correct

• E₁ < E₂ < E₃
• E₁ > E₂ = E₃
• E₁ = E₂ < E₃
• E₁ > E₂ > E₃

E₁ < E₂ < E₃

Ques 2: Silicon is doped with which of the following to obtain P type semiconductor

• Phosphorus
• Gallium
• Germanium
• Bismuth

Gallium

Ques 3: What happens to resistance of an intrinsic semiconductor when heated

• increases
• remains constant
• decreases
• decreases linearly

decreases

Ques 4: A semiconductor has an electron concentration of 6 × 10²² per m³ and hole concentration of 8.5 × 10⁹ per m³. The it is

• N type semiconductor
• P type semiconductor
• intrinsic semiconducotr
• conductor

N type semiconductor

Ques 5: What type of doping is used in Zener diode

• light
• moderate
• heavy
• no doping

heavy

Ques 6: In an n-type silicon, which of the following statement is true:

• Electrons are majority carriers and trivalent atoms are the dopants.
• Electrons are minority carriers and pentavalent atoms are the dopants.
• Holes are minority carries and pentavalent atoms are the dopants.
• Holes are majority carries and trivalent atoms are the dopants.

Holes are minority carries and pentavalent atoms are the dopants.

Ques 7: Carbon, silicon and germanium have four valence electrons each. These are characterized by valence and conduction bands separated by energy band gap respectively equal to (E_g)_C, (E_gSi and (E_g)_Ge. Which of the following statements is ture?

• (E_g)_Si < (E_g)_Ge < (E_g)_C
• (E_g)_C < (E_g)_Ge < (E_g)_Si
• (E_g)_C > (E_g)_Si > (E_g)_Ge
• (E_g)_C < (E_g)_Si < (E_g)_Ge

(E_g)_C > (E_g)_Si > (E_g)_Ge

Ques 8: In an unbiased p-n junction, holes diffuse from the p-region to n-region because

• free electrons in the n-region attract them.
• they move across the junction by the potential difference
• hole concentration in p-region is more as compared to n-region.
• All the above.

hole concentration in p-region is more as compared to n-region.

Ques 9: When a forward bias is applied to a p-n junction, it

• raises the potential barrier.
• reduces the majority carrier current to zero.
• lower the potential barrier.
• none of the above

lower the potential barrier.

Ques 10: In a p-type silicon, which of the following statement is ture:

• Electrons are majority carriers and trivalent
• ELectorns are minority carriers and pentavalent atoms are the dopants.
• Holes are minority carries and pentavalent atoms are the dopants.
• Holes are majority carries and trivalent atoms are the dopants.

Holes are majority carries and trivalent atoms are the dopants.

Ques 11: The intrinsic semiconductor becomes an insulator at

• 0⁰C
• -100⁰C
• 300 K
• 0 K

0 K

Ques 12: In the forward bias arrangement of a PN-Junction diode

• The N-end is connected to the positive terminal of the battery
• The P-end is connected to the positive terminal of the battery
• The direction of current is from N-end to P-end in the diode
• The P-end is connected to the negative terminal of battery

The P-end is connected to the positive terminal of the battery

Ques 13: In a PN-Junction diode

• The current in the reverse biased condition is generally very small – μA
• The current in the reverse biased condition is independent of the bias voltage
• The reverse biased current is strongly dependent on the applied bias voltage
• The forward biased current is very small in comparison to reverse biased current

The current in the reverse biased condition is generally very small – μA

Ques 14: A P-type semiconductor can be obtained by adding

• Arsenic to pure silicon
• Gallium to pure silicon
• Antimony to pure germanium
• Phosphorous to pure germanium

Gallium to pure silicon

Ques 15: Electrical conductivity of a semiconductor

• • Decreases with the rise in its temperature
  • Increases with the rise in its temperature
  • Does not change with the rise in its temperature
  • First increases and then decreases with the rise

  Increases with the rise in its temperature

Ques 16: The cut-in voltage for silicon diode is approximately

• 0.2 V
• 0.6 V
• 1.1 V
• 1.4 V

0.6 V

Ques 17: The depletion layer in the P-N junction region is caused by

• Drift of holes
• Diffusion of charge carriers
• Migration of impurity ions
• Drift of electrons

Diffusion of charge carriers

Ques 18: Which is reverse biased diode

b

Ques 19: If a full wave rectifier circuit is operating from 50 Hz main, the fundamental frequency in the ripple will be

• 50 Hz
• 70.7 Hz
• 100 Hz
• 2.5 Hz

100 Hz

Ques 20: What is the current in the cirucit shown in

• 0.2 V
• 0.6 V
• 1.1 V
• 1.4 V

0.6 V

Ques 21: The energy gap between conduction band and valence band is of order of 0.07 V. it is a/an

• insulator
• conductor
• semiconductor
• alloy

conductor