Free PN Junction MCQs with Answers
115 PN Junction 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 PN junction forms when p type and n type semiconductor regions meet, creating a depletion layer and a potential barrier. The topic covers forward and reverse bias, diode current voltage characteristics, breakdown and rectification, while distinguishing an ordinary junction diode from a transistor formed from multiple junctions.
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- A. Conductors
- B. Insulators
- C. Semi conductors
- D. All of the above
Explanation: A hole is an unoccupied position in the valence band and behaves as a positive charge carrier in a semiconductor.
Correct answer: Semi conductors- A. Face centred cubic
- B. Body centred cubic
- C. Simple cubic
- D. All of the above
Explanation: Common elemental semiconductors such as silicon and germanium have the diamond cubic structure, whose underlying Bravais lattice is…
Correct answer: Face centred cubic- A. Semi conductor
- B. Super conductors
- C. Insulators
- D. Conductor
Explanation: Insulators have valence electrons strongly bound to their atoms, so very few electrons are available for electrical conduction, especially…
Correct answer: Insulators- A. Energy state
- B. Valence band
- C. ve energy state
- D. conduction band
Explanation: The valence band is the allowed energy band containing the valence electrons of a solid.
Correct answer: Valence band- A. rotory
- B. photovoltaic
- C. galvanic
- D. non of these
Explanation: Photovoltaic cells convert sunlight directly into electrical energy through the photovoltaic effect in a semiconductor junction.
Correct answer: photovoltaic- A. 100-1000eV
- B. 0.5-10eV
- C. 0.01-0.1 eV
- D. 10000-10000000eV
Explanation: Students have to learn this value as it is a fact that the range of a typical band gap in conductors is from 0.01 to 0.1 eV.
Correct answer: 0.01-0.1 eV- A. 150
- B. 250
- C. 300
- D. none
Explanation: The current gain of a transistor, also known as beta (β), is calculated by dividing the collector current (Ic) by the base current (Ib):β…
Correct answer: 250- A. Doping
- B. Temperature
- C. Voltage
- D. Pressure
Explanation: Pressure is the factor that does not affect the conductivity of a PN junction diode.
Correct answer: Pressure- A. 0.3v
- B. 0.5V
- C. 0.7V
- D. 1.1V
Explanation: The knee voltage for Germanium is approximately 0.3 volts. This is the point in the forward bias of a diode at which the current starts to…
Correct answer: 0.3v- A. 5.85A
- B. 1.15A
- C. 1.48A
- D. 0.67A
Explanation: IB =IE −IC Where:( IE ) is the emitter current( IC ) is the collector currentGiven that the emitter current ( IE ) is 3.5 A and the…
Correct answer: 1.15A- A. 0.3 V
- B. 0.7 V
- C. 0.5 V
- D. 5.0 V
Explanation: The potential difference across a silicon PN junction is 0.7 volt.
Correct answer: 0.7 V- A. Gallium
- B. Indium
- C. Germinium
- D. Silicon
Explanation: A potential barrier of 0.7 volts across a P-N junction is typically associated with a junction made from silicon.
Correct answer: Silicon53. If in a transistor both collector-base and base-emitter junctions are reversed biased then it is:
- A. Cut-off region
- B. region Act
- C. Active region
- D. point
Explanation: In a typical operation one junction (the base-emitter junction) is forward biased while the other (the base-collector junction) is reverse…
Correct answer: Cut-off region54. The type of impurity that has to be added to a semiconductor material so that it can provideholes is
- A. trivalent.
- B. tetravalent.
- C. pentavalent.
- D. monovalent.
Explanation: The type of impurity that needs to be added to a semiconductor material to provide holes is A) trivalent.Explanation:When a trivalent…
Correct answer: trivalent.- A. one input become low (0).
- B. one input become high (1).
- C. both inputs become low (0).
- D. both inputs become high (1).
Explanation: * Input A is 0, Input B is 0 (both inputs are low) * Input A is 0, Input B is 1 (one input is low) * Input A is 1, Input B is 0 (one input…
Correct answer: one input become low (0).56. The CORRECT symbol of a n-p-n transistor is(Note: Where 'E', 'B' and 'C' have their usual meaning.)
- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: The correct symbol of a n-p-n transistor is Emitter-Base-Collector, where the arrow points in the direction of conventional current flow.
Correct answer: Option A- 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