ETC EngineeringMCQs
Home

Special Diodes MCQs

Practice Special Diodes MCQs with four options, answers and explanations for focused Electronics & Telecommunication Engineering revision.

Question 1
Electronic Devices & CircuitsSpecial Diodes

A Zener diode is normally operated for voltage regulation in its?

  • AForward cut-off region
  • BReverse breakdown region
  • CZero-current region only
  • DForward saturation region
Report an error
Correct Answer: B. Reverse breakdown region
Explanation: A Zener diode is designed to operate safely in reverse breakdown, where its voltage remains approximately constant over a useful current range.
Reference: Standard electronics: Zener diode
Question 2
Electronic Devices & CircuitsSpecial Diodes

A photodiode used as a light detector is commonly operated under?

  • AReverse bias
  • BHeavy forward bias only
  • CZero voltage in every application
  • DAvalanche breakdown necessarily
Report an error
Correct Answer: A. Reverse bias
Explanation: Photodiodes are commonly reverse biased so incident light produces a measurable photocurrent with useful response speed and sensitivity.
Reference: Standard optoelectronics: photodiode
Question 3
Electronic Devices & CircuitsSpecial Diodes

An LED emits light primarily because of?

  • ACarrier recombination in a forward-biased junction
  • BReverse-bias leakage only
  • CThermal breakdown of the junction
  • DMechanical vibration of the package
Report an error
Correct Answer: A. Carrier recombination in a forward-biased junction
Explanation: In an LED, injected electrons and holes recombine in the semiconductor and release energy as photons.
Reference: Standard optoelectronics: LED
Question 5
Electronic Devices & CircuitsSpecial Diodes

A varactor diode is primarily used as a voltage-controlled?

  • ACapacitance
  • BCurrent source
  • CInductance heater
  • DOptical amplifier
Report an error
Correct Answer: A. Capacitance
Explanation: A reverse-biased varactor exploits the voltage dependence of PN-junction capacitance, making it useful for electronic tuning.
Reference: Standard electronics: varactor diode
Question 6
Electronic Devices & CircuitsSpecial Diodes

A Schottky diode generally switches faster than an ordinary PN diode mainly because it is primarily a?

  • AMajority-carrier device with little minority-carrier charge storage
  • BDevice with an extremely thick depletion region only
  • CLight-emitting junction
  • DCurrent-controlled transistor
Report an error
Correct Answer: A. Majority-carrier device with little minority-carrier charge storage
Explanation: Schottky conduction mainly involves majority carriers, so there is little minority-carrier storage and reverse-recovery delay is small.
Reference: Standard electronics: Schottky diode
Question 7
Electronic Devices & CircuitsSpecial Diodes

A PIN diode contains which structure between its heavily doped P and N regions?

  • AA relatively wide intrinsic region
  • BA metallic collector
  • CA second gate oxide
  • DA permanent short circuit
Report an error
Correct Answer: A. A relatively wide intrinsic region
Explanation: A PIN diode has a P-I-N structure. The intrinsic region gives useful RF switching, attenuation, and photodetection characteristics.
Reference: Standard electronics: PIN diode
Question 8
Electronic Devices & CircuitsSpecial Diodes

At radio frequencies, a forward-biased PIN diode is often used approximately as a?

  • ACurrent-controlled RF resistance
  • BZener reference only
  • CLight source only
  • DNegative capacitor only
Report an error
Correct Answer: A. Current-controlled RF resistance
Explanation: Stored charge in the intrinsic region makes a forward-biased PIN diode behave approximately as a controllable low RF resistance, useful in RF switches and attenuators.
Reference: Standard electronics: PIN diode RF application
Question 9
Electronic Devices & CircuitsSpecial Diodes

A tunnel diode exhibits a region of negative differential resistance because of?

  • AQuantum-mechanical tunneling in a very heavily doped junction
  • BOrdinary transformer action
  • CMechanical vibration
  • DAvalanche multiplication only
Report an error
Correct Answer: A. Quantum-mechanical tunneling in a very heavily doped junction
Explanation: Heavy doping creates a very narrow junction that permits quantum tunneling. Over part of its characteristic, current decreases as voltage increases, producing negative differential resistance.
Reference: Standard electronics: tunnel diode
Question 10
Electronic Devices & CircuitsSpecial Diodes

A Schottky barrier junction is formed primarily between?

  • AA metal and a semiconductor
  • BTwo identical metal wires
  • CTwo insulating layers only
  • DA BJT collector and emitter short
Report an error
Correct Answer: A. A metal and a semiconductor
Explanation: A Schottky diode uses a rectifying metal-semiconductor junction rather than a conventional PN junction.
Reference: Standard semiconductor electronics: Schottky barrier
Question 11
Electronic Devices & CircuitsSpecial Diodes

The forward voltage of a silicon Schottky diode at ordinary current levels is commonly lower than that of a silicon PN diode mainly because of its?

  • AMetal-semiconductor majority-carrier conduction mechanism
  • BMuch larger band gap
  • CRequired avalanche operation
  • DOptical emission
Report an error
Correct Answer: A. Metal-semiconductor majority-carrier conduction mechanism
Explanation: Schottky junction conduction is a majority-carrier process and typically gives a lower forward drop than an ordinary silicon PN diode at comparable current.
Reference: Standard electronics: Schottky forward voltage