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. 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- 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. Equal to D.C. value
- B. More than D.C. value
- C. Less than D.C. value
- D. Zero
Explanation: For a half-wave rectified sine wave with peak current I0, the total rms current is I0/2 and the DC current is I0/pi.
Correct answer: More than D.C. value- A. Converter
- B. A rectifier
- C. Inverter
- D. Oscillator
Explanation: An inverter uses electronic switching to convert direct current into alternating current.
Correct answer: Inverter53. In half-wave rectification the output D.C. voltages is obtained across the load for_______________?
- A. The negative half cycle of A.C.
- B. The positive half cycle of A.C.
- C. The positive and negative half cycles
- D. Either positive or negative half of A.C.
Explanation: In a half-wave rectifier, the diode conducts during only one half-cycle and blocks the other half-cycle, producing output across the load…
Correct answer: The positive half cycle of A.C.54. In full wave rectification the output D.C. voltage across the load is obtained for_____________?
- A. The positive half cycle of input A.C.
- B. The negative half cycle of input A.C.
- C. The complete cycle of input A.C.
- D. All of the above.
Explanation: A full-wave rectifier uses both the positive and negative half cycles of the AC input, but reverses the negative half so the load current…
Correct answer: The complete cycle of input A.C.- A. using a transistor
- B. suppressing the harmonics in A.C voltage
- C. suppressing half wave of A.C supply by using diode
- D. using a Coolidge tube
Explanation: A diode conducts readily in forward bias and blocks current in reverse bias, so placing it in an AC circuit allows one half cycle to pass…
Correct answer: suppressing half wave of A.C supply by using diode- A. An amplifier.
- B. A rectifier
- C. Filtering circuit
- D. Converter.
Explanation: A rectifier changes alternating voltage or current into a unidirectional, pulsating DC output, usually by using diodes.
Correct answer: A rectifier- A. It has low resistance to the current flow when forward biased & high resistance when reverse biased.
- B. It has low resistance to the current flow when forward biased.
- C. It has high resistance to the current flow when reverse biased
- D. Its conductivity increases with rise of temperature.
Explanation: A diode rectifies because its low forward resistance permits substantial current in one direction, while its high reverse resistance…
Correct answer: It has low resistance to the current flow when forward biased & high resistance when reverse biased.- 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. 25
- B. 50
- C. 100
- D. 75
Explanation: Option A) 25 is not correct because it does not correspond to the frequency of the AC input or the number of pulses in the rectifier…
Correct answer: 50- A. Lower half cycle
- B. Upper half cycle
- C. Both cycles
- D. None of them
Explanation: The rectifier circuit that converts alternating current into the direct current is known as a halfwave rectifier circuit.
Correct answer: Upper half cycle