Semiconductor Diode MCQs for NEET

A semiconductor diode conducts current in one direction. The diodes are two-terminal devices that consist of PN junction. The diode can be forward biased or reverse biased. Forward biased meaning p-side of the diode is connected to the positive terminal and n-side is connected to the negative terminal. In reverse bias p-side is connected to the negative terminal of the battery and n-side is connected to the positive terminal. The different types of semiconductor diodes are

  • LED
  • Zener diode
  • Rectifier diode
  • Tunnel diode
  • Variable capacitance diode
  • Photodiode
  • Switching diode
  • Gunn diode

Q1: In the forward bias arrangements of a PN junction diode

  1. The N end is connected to the positive terminal of the battery
  2. The P end is connected to the positive terminal of the battery
  3. The direction of the current is from N end to the P end in the diode
  4. The P end is connected to the negative terminal of the battery

Answer: (b) The P end is connected to the positive terminal of the battery

Q2: In a PN junction diode

  1. The current in the reverse biased condition is generally very small
  2. The current in the reverse biased condition is generally very small but the forward-biased current is independent of the bias voltage
  3. The reverse-biased current is strongly dependent on the applied bias voltage
  4. The forward biased current is very small in comparison to reverse-biased current.

Answer: (a) The current in the reverse biased condition is generally very small

Q3: The cut-in voltage for silicon diode is approximately

  1. 0.2 V
  2. 0.6 V
  3. 1.1 V
  4. 1.4 V

Answer: (b) 0.6 V

Q4: The electrical resistance of the depletion layer is large because

  1. It has no change carriers
  2. It has a large number of charge carriers
  3. It contains electrons as charge carriers
  4. It has holes as charge carriers

Answers: (a) It has no change carriers

Q5: If the forward voltage in a semiconductor diode is doubled, the width of the depletion layer will

  1. Become half
  2. Become one-fourth
  3. Remain unchanged
  4. Become double

Answer: (a) Become half

Q6: The PN junction diode is used as

  1. An amplifier
  2. A rectifier
  3. An oscillator
  4. A modulator

Answer: (b) A rectifier

Q7: When a PN junction diode is reverse biased

  1. Electrons and holes are attracted towards each other and move towards the depletion region
  2. Electrons and holes move away from the junction depletion region
  3. Height of the potential barrier decreases
  4. No change in the current takes place

Answer: (b) Electrons and holes move away from the junction depletion region

Q8: A PN junction has a thickness of the order

  1. 1 cm
  2. 1 mm
  3. 10-6 m
  4. 10-12 cm

Answer: (c) 10-6 m

Q9: In the depletion region of an unbiased PN junction diode there are

  1. Only electrons
  2. Only holes
  3. Both electrons and holes
  4. Only fixed ions

Answer: (d) Only fixed ions

Q10: On increasing the reverse bias to a large value in a PN junction diode, current

  1. Increases slowly
  2. Remains fixed
  3. Suddenly increases
  4. Decreases slowly

Answer: (c) Suddenly increases

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