Electronics

Electronics MDCAT MCQs with answers

38 past paper MCQs from Physics unit 13, Electronics, across 2 topics. They are arranged topic by topic; bigger topics show a sample here and link to their full set and to study notes. Tap “Show answer” for the correct option and a short solution.

Practise as a quiz

The PN Junction and its Biasing

1.A diode characteristic curve is a plot between: (MDCAT 2024)

  1. current and time
  2. voltage and time
  3. voltage and current
  4. reverse voltage and forward voltage
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Correct answer: (c) voltage and current

The characteristic curve of a diode plots the current through it against the voltage across it.

2.Which of the following is NOT true about an LED? (UHS MDCAT 2017)

  1. two wires, called leads, are attached to an LED
  2. while connecting it in a circuit, the longer lead of the LED is always connected to the positive terminal of the battery
  3. while connecting it in a circuit, the shorter lead of the LED is always connected to the positive terminal of the battery
  4. an LED can be used to detect weak current
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Correct answer: (c) while connecting it in a circuit, the shorter lead of the LED is always connected to the positive terminal of the battery

The longer lead is the anode and goes to the positive terminal, so the statement about the shorter lead is the false one.

3.Which of the following is false? (UHS MDCAT 2017)

  1. in a p-type substance the majority charge carriers are holes
  2. during forward biasing of a diode the width of the depletion region decreases
  3. the leakage current is due to minority charge carriers
  4. none of the given options
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Correct answer: (d) none of the given options

All three statements are correct, so none of them is false.

All 9 The PN Junction and its Biasing MCQs → The PN Junction and its Biasing notes →

Rectification

4.The conversion of A.C. into D.C. is called rectification and the circuit is called a rectifier. Which component of electronics acts as a rectifier? (MDCAT 2024)

  1. diode
  2. transistor
  3. transformer
  4. inductor
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Correct answer: (a) diode

A diode conducts in one direction only, which is what rectification needs.

5.Full wave rectification is given by: (MDCAT 2024)

  1. one diode connected in a bridge type arrangement
  2. two diodes connected in a bridge type arrangement
  3. three diodes connected in a bridge type arrangement
  4. four diodes connected in a bridge type arrangement
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Correct answer: (d) four diodes connected in a bridge type arrangement

The bridge rectifier uses four diodes, so both halves of the cycle drive the load the same way.

6.In a full-wave rectifier using two diodes, the diodes: (KMU MDCAT 2025)

  1. D1 and D2 operate:
  2. Simultaneously during both half-cycles
  3. In alternate switching mode
  4. Only when both ends of transformer are positive
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Correct answer: (c) In alternate switching mode

Each diode conducts on the half cycle that makes its end of the secondary positive, so they take turns.

All 29 Rectification MCQs → Rectification notes →

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