MCQs on PN junction diode for NEET 2020

The interface or the boundary between the p-type and n-type semiconductor is called PN junction. The p-side has an excess of holes and n-type has an excess of electrons.

PN junction

Q1: In a PN junction with no external voltage, the electric field between acceptor and donor ion is called a

  1. Peak
  2. Barrier
  3. Threshold
  4. Path

Answer: (b) Barrier

Q2: In a PN junction the potential barrier is due to the charges on either side of the junction, these charges are

  1. Majority carriers
  2. Minority carriers
  3. Both (a) and (b)
  4. Fixed donor and accepter ions

Answer: (d) Fixed donor and accepter ions

Q3: The capacitance of a reverse-biased PN junction

  1. Increases as reverse bias is increased
  2. Decreases as reverse bias is increased
  3. Increases as reverse bias is decreased
  4. Is significantly low

Answer: (c) Increases as reverse bias is decreased

Q4: For a PN junction diode, the current in reverse bias maybe

  1. Few milliamperes
  2. Between 0.2 A and 15 A
  3. Few amperes
  4. Few micro or nano amperes

Answer: (d) Few micro or nano amperes

Q5: When PN junction is in forward bias, by increasing the battery voltage

  1. Circuit resistance increases
  2. Current through P_N junction increases
  3. Current through P_N junction decreases
  4. None of the above

Answer: (b) Current through P_N junction increases

Q6: When a PN junction is reverse biased

  1. Holes and electrons tend to concentrate towards the junction
  2. The barrier tends to break down
  3. Holes and electrons tend to move away from the junction
  4. None of these

Answer: (c) Holes and electrons tend to move away from the junction

Q7: A PN junction

  1. Has low resistance in forward as well as reverse directions
  2. Has high resistance in forward as well as reverse directions
  3. Conductors in the forward direction only
  4. Conducts in the reverse direction only

Answer: (c) Conductors in the forward direction only

Q8: A PN junction is said to be forward-biased when

  1. The positive terminal of the battery is connected to P-side and the negative side to the N-side
  2. Junction is earthed
  3. N-side is connected directly to the p-side
  4. The positive terminal of the battery is connected to N-side and the negative side to the P-side.

Answer: (a) The positive terminal of the battery is connected to P-side and the negative side to the N-side

Q9: PN junction failure below 5 V is caused primarily by

  1. Avalanche breakdown
  2. Zener breakdown
  3. Either (a) or (b)
  4. None of the above

Answer: (b) Zener breakdown

Q10: In a reverse-biased PN junction, the current through the junction increases abruptly at

  1. 0.5 V
  2. 1.1 V
  3. 0.72 V
  4. Breakdown voltage

Answer: (d) Breakdown voltage

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