JSMU Karachi Entry Test Physics: Electronics MCQs

Practice Electronics MCQs for JSMU Karachi Entry Test Physics — topic-wise sets with solved answers.

JSMU Karachi Entry Test Physics: Electronics MCQs — sample questions

  1. Question 1

    Q1. In an NPN transistor, the majority charge carriers in the base region are

    • A) electrons
    • B) holes
    • C) protons
    • D) neutrons

    Answer: holes

    Explanation: Holes are majority carriers in the P-type base region. Electrons are majority carriers in N-type regions.

  2. Question 2

    Q2. The input resistance of an ideal operational amplifier is

    • A) zero
    • B) very low
    • C) very high
    • D) infinite

    Answer: infinite

    Explanation: Ideal op-amp has infinite input resistance. Real op-amps have very high input resistance.

  3. Question 3

    Q3. A Zener diode is used as a

    • A) rectifier
    • B) voltage regulator
    • C) amplifier
    • D) oscillator

    Answer: voltage regulator

    Explanation: Zener diodes regulate voltage due to their specific reverse breakdown voltage.

  4. Question 4

    Q4. The gain of a common emitter amplifier is given by

    • A) R_E/R_B
    • B) R_C/R_E
    • C) R_C/R_B
    • D) β*R_C/R_B

    Answer: β*R_C/R_B

    Explanation: Common emitter gain is β times the ratio of collector resistance to base resistance.

  5. Question 5

    Q5. The width of the depletion region in a PN junction diode increases when

    • A) forward biased
    • B) reverse biased
    • C) at zero bias
    • D) at high temperature

    Answer: reverse biased

    Explanation: Reverse bias increases depletion width. Forward bias decreases it.

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