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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115 questions · page 2 of 6
- A. 2
- B. 3
- C. 4
- D. 5Education
Explanation: Silicon has four valence electrons, so doping it with a trivalent atom leaves one incomplete bond and produces a hole, making the crystal…
Correct answer: 3- A. Step up transformer
- B. Step down transformer
- C. Three diodes in common
- D. Triode vacuum tube
Explanation: A transistor amplifier, like a triode vacuum tube, uses a small input signal to control a much larger output signal through a controlled…
Correct answer: Triode vacuum tube- A. Non-inverting voltage at output
- B. Reference voltage on the other
- C. Virtual input
- D. Output
Explanation: An op-amp comparator compares the voltage applied to one input with a reference voltage applied to the other input, and its output…
Correct answer: Reference voltage on the other- A. That the emitter be heated
- B. That the base be heated
- C. That the collector be heated
- D. None of the above
Explanation: A transistor operates through electrical biasing of its emitter, base, and collector junctions; none of these regions must be heated for…
Correct answer: None of the above- A. 2
- B. 3
- C. 4
- D. 5
Explanation: Germanium has four valence electrons, and doping it with a pentavalent impurity supplies one extra free electron, producing an n-type…
Correct answer: 5- A. A high gain amplifier
- B. A high-power amplifier
- C. A high resistance amplifier
- D. A low resistance amplifierStereo Systems & Components
Explanation: An operational amplifier is designed to have a very large open-loop voltage gain, so even a small differential input can produce a…
Correct answer: A high gain amplifier- A. is located on the emitter
- B. is located on the base
- C. is locate on the collector
- D. points form north to south
Explanation: The arrow in a transistor symbol is placed on the emitter and shows the direction of conventional current, with NPN pointing out and PNP…
Correct answer: is located on the emitter- A. antimony
- B. phosphorus
- C. aluminium
- D. arsenic
Explanation: Antimony, phosphorus and arsenic are pentavalent impurities, so they donate an extra electron to silicon or germanium and form n-type…
Correct answer: aluminium- A. minority carriers
- B. majority carriers
- C. holes
- D. electron
Explanation: In forward bias, the potential barrier and depletion width decrease, allowing the abundant majority carriers to cross the junction and…
Correct answer: majority carriers- A. during the manufacturing process
- B. under forward bias
- C. under reverse bias
- D. when temperature varies
Explanation: When p-type and n-type materials are joined, majority carriers diffuse across the junction and leave fixed ions behind, creating the…
Correct answer: during the manufacturing process- A. equal to emitter current
- B. slightly less than emitter current
- C. greater than emitter current
- D. any of above
Explanation: The emitter current divides into collector and base currents according to Ie = Ic + Ib, so the collector current is slightly less than the…
Correct answer: slightly less than emitter current- A. n
- B. p
- C. mix
- D. any of above
Explanation: A donor atom contributes an extra electron to the crystal, making free electrons the majority carriers and producing an n-type…
Correct answer: n- A. The switch
- B. The light emitting diode
- C. The photo diodes
- D. Solar cells.
Explanation: A light-emitting diode produces light when electrons and holes recombine at a forward-biased junction and release energy as photons.
Correct answer: The light emitting diode- A. insulator
- B. conductor
- C. semi conductor
- D. any of aboveOrdering Wholesale Electronic Components For Circuits
Explanation: Insulators have the largest forbidden energy gap, so electrons require much more energy to move from the valence band to the conduction…
Correct answer: insulator- A. holes in n-type and free electrons in p-type
- B. holes in n-type and p-type
- C. free electrons in n-type and holes in p-type
- D. free electrons in n-type and p-type
Explanation: In n-type material, electrons are majority carriers, so holes are minority carriers; in p-type material, holes are majority carriers, so…
Correct answer: holes in n-type and free electrons in p-type- A. collector
- B. emitter
- C. base
- D. any of above
Explanation: An n-p-n transistor has two n-type regions, the emitter and collector, separated by a thin p-type base.
Correct answer: base- A. pentavalent
- B. trivalent
- C. divalent
- D. tetravalent
Explanation: Silicon and germanium each have four valence electrons, so they are tetravalent elements and form covalent crystals.
Correct answer: tetravalent- A. majority carriers
- B. minority carriers
- C. dual carriers
- D. blockers
Explanation: In p-type material, holes are introduced as the majority carriers, while electrons produced by thermal generation are present in much…
Correct answer: minority carriers- A. Positive
- B. Negative
- C. Both positive and negative
- D. Neutral
Explanation: An n-type semiconductor has extra electrons as majority carriers, but the donor ions left in the lattice are positively charged, so the…
Correct answer: Neutral- A. Holes only
- B. Electrons only
- C. Electron and holes both
- D. All of the above
Explanation: Semiconductors conduct through both free electrons in the conduction band and holes in the valence band.
Correct answer: Electron and holes both