Free Electronics MCQs with Answers
660 Electronics MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
A p-n junction forms when p-type and n-type semiconductor regions meet, creating a depletion layer, barrier potential and rectifying action. The work covers forward and reverse bias, junction current, diode characteristics, and how a diode converts alternating current into pulsating direct current through half-wave and full-wave rectification.
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- A. A
- B. B
- C. C
- D. D
Explanation: The output of an AND gate is 1 (High) only when both inputs are 1 (High).
Correct answer: B- A. Option A: Silicon
- B. Option B: Germanium
- C. Option C: Gallium
- D. Option D: Carbon
Explanation: The correct answer is Option A: Silicon. When doped with electron-rich impurities, silicon becomes an n-type semi-conductor.
Correct answer: Option A: Silicon- A. is low
- B. is zero
- C. is high
- D. varies
Explanation: In forward biasing, a p-n junction diode experiences a reduction in resistance due to the application of an external voltage that allows…
Correct answer: is low- A. photo diode
- B. electrolytic cell
- C. photo voltaic cell
- D. light emitting diode
Explanation: An electrolytic cell is not a semiconductor device and is not based on a p-n junction.
Correct answer: electrolytic cell- A. Divalent
- B. Trivalent
- C. Pentavalent
- D. Monovalent
Explanation: Divalent impurities are used to convert a pure semi-conductor into a p-type semi-conductor because they introduce holes in the crystal…
Correct answer: Divalent- A. I only.
- B. II only.
- C. I and III.
- D. II and III.
Explanation: In a p-n junction, the forward current is typically more than the reverse current.
Correct answer: II and III.- A. potential barrier.
- B. depletion region.
- C. interaction region.
- D. absolute potential.
Explanation: When free electrons move from the n-region to the p-region in a semiconductor device, the potential difference that appears across this…
Correct answer: interaction region.- A. holes
- B. protons
- C. electrons
- D. positrons
Explanation: In a p-type semiconductor, the majority charge carriers are holes, which are essentially the absence of electrons.
Correct answer: holes- A. II only.
- B. III only.
- C. I and II.
- D. I and III.
Explanation: The correct answer is Option A: II only. An LED emits light only when it is reverse biased.
Correct answer: II only.- A. reverse biased.
- B. forward biased.
- C. positively biased.
- D. negatively biased.
Explanation: In a p-n junction diode, when the p-side is at a negative potential with respect to the n-side, the diode is said to be reverse biased.
Correct answer: reverse biased.- A. Barium
- B. Sodium
- C. Aluminium
- D. Germanium
Explanation: Germanium is the correct answer because it is a tetravalent semiconductor, meaning it has four valence electrons.
Correct answer: Germanium- A. one.
- B. two.
- C. three.
- D. four.
Explanation: Transistors have four terminals in total, which include the emitter, base, collector, and sometimes the substrate terminal.
Correct answer: four.- A. Inductor.
- B. Conductor.
- C. Open switch.
- D. Closed switch.
Explanation: A reverse-biased semiconductor diode acts like an open switch because it does not allow current to flow under reverse bias conditions.
Correct answer: Open switch.- A. Base.
- B. Emitter.
- C. Collector.
- D. Depletion layer.
Explanation: In a transistor, the collector is typically the largest component. This is because it needs to efficiently collect and dissipate the heat…
Correct answer: Collector.- A. OR gate
- B. NOT gate
- C. AND gate
- D. XNOR gate
Explanation: When the two inputs of a NAND gate are connected together, the gate behaves like a NOT gate.
Correct answer: NOT gate- A. XOR gate
- B. NOR gate
- C. XNOR gate
- D. NAND gate
Explanation: The most suitable logic gate for a security alarm intended to detect changes or tampering with luggage is the XOR gate.
Correct answer: XOR gate- A. OR gate
- B. NOT gate
- C. AND gate
- D. NOR gate
Explanation: The correct answer is the OR gate. An OR gate outputs true when at least one of its inputs is true, which aligns with the given circuit…
Correct answer: OR gate- A. Zero charge.
- B. Infinite charge.
- C. Positive charge.
- D. Negative charge.
Explanation: In a p-n junction diode, the depletion region is formed when the free electrons and holes near the junction recombine, leaving behind…
Correct answer: Zero charge.- A. Only a trivalent impurity is added to it.
- B. Only a pentavalent impurity is added to it.
- C. Both trivalent and pentavalent impurities are added to it.
- D. Both trivalent and pentavalent impurities are removed from it.
Explanation: An n-type semiconductor is formed when a pentavalent impurity, such as phosphorus, is added to the semiconductor material.
Correct answer: Only a pentavalent impurity is added to it.- A. Resisted.
- B. Inverted.
- C. Enhanced.
- D. Re-complemented.
Explanation: A NOT gate, also known as an inverter, takes an input signal and outputs the opposite state: if the input is high (1), the output will be…
Correct answer: Inverted.