MCQs on Junction Transistor for NEET 2020

A bipolar junction transistor is a semiconductor device with three terminals and two p-n junctions. The three terminals are named as the base, emitter and collector. The small-amplitude signal applied at the base is amplified at the collector. The Bipolar Junction transistor is of two types, NPN transistor and PNP transistor, based on the doping types of the three terminals.

Q1. The emitter-base junction of a transistor is ………. Biased while the collector-base junction is ………….

  1. Reverse, Forward
  2. Reverse, Reverse
  3. Forward, forward
  4. Forward, reverse

Answer: (d) Forward, reverse

Q2: A NPN transistor conducts when

  1. Both collector and emitter are positive with respect to the base
  2. Collector is positive and the emitter is negative with respect to the base
  3. Collector is positive and the emitter is at the same potential as the base
  4. Both collector and emitter are negative with respect to the base

Answer: (b) Collector is positive and the emitter is negative with respect to the base

Q3: Which of the following is true

  1. Common base transistor is commonly used because the current gain is maximum
  2. Common emitter is commonly used because the current gain is maximum
  3. Common collector is commonly used because the current gain is maximum
  4. Common emitter is the least used transistor

Answer: (b) Common emitter is commonly used because the current gain is maximum

Q4: For a common base configuration of PNP transistor Ic/IE = 0.98 then the maximum current gain in common emitter configuration will be

  1. 12
  2. 24
  3. 6
  4. 5

Answer: (b) 24

Q5: In a PNP transistor working as a common-base amplifier, the current gain is 0.96 and emitter current is 7.2 mA. The base current is

  1. 0.4 mA
  2. 0.2 mA
  3. 0.29 mA
  4. 0.35 mA

Answer: (c) 0.29 mA

Q6: Which is the least doped region in a transistor?

  1. Either emitter or collector
  2. Base
  3. Emitter
  4. Collector

Answer: (b) Base

Q7: The transistors provide good power amplification when they are used in

  1. Common collector configuration
  2. Common emitter configuration
  3. Common base configuration
  4. None of these

Answer: (b) Common emitter configuration

Q8: For a transistor the parameter b= 99. The value of the parameter is a is

  1. 0.9
  2. 0.99
  3. 1
  4. 9

Answer: (b) 0.99

Q9: A transistor is used in common emitter mode as an amplifier. Then

  1. The base-emitter junction will be forward biased
  2. The input signal is connected in series with the voltage applied to the base-emitter junction
  3. The base-emitter junction will be reversed biased
  4. The voltage applied to bias the base-collector junction and the input signal is connected in series

Answer: (b) The input signal is connected in series with the voltage applied to the base-emitter junction

Q10: In a PNP transistor the base is the N-region. Its width relative to the P-region is

  1. Smaller
  2. Larger
  3. Same
  4. Not related

Answer: (a) Smaller

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