Free Electronics and Devices MCQs with Answers

• A. 1 : 1
• B. 100 : 1
• C. 1000 : 1
• D. 40,000 : 1

Explanation: A germanium diode conducts readily in the forward direction but offers very high opposition in reverse bias.

• A. kΩ
• B. Ω
• C. MΩ
• D. none of the above

Explanation: When forward biased, a crystal diode has a relatively small resistance, usually of the order of a few ohms.

• A. an amplifier
• B. a rectifier
• C. an oscillator
• D. a voltage regulator

Explanation: A diode conducts mainly in one direction, allowing it to convert alternating current into pulsating direct current in a rectifier.

• A. forward
• B. reverse
• C. either forward or reverse
• D. none of the above

Explanation: The stated polarity makes the arrow side positive relative to the bar side, placing the diode's anode at a higher potential than its…

• A. 2.5 V
• B. 3 V
• C. 10 V
• D. 0.7 V

Explanation: A silicon pn-junction diode has a forward knee voltage of approximately 0.7 V at ordinary operating currents.

• A. one pn junction
• B. two pn junctions
• C. three pn junctions
• D. none of the above

Explanation: A crystal diode is formed from a single p-type to n-type junction, hence it has one pn junction.

• A. non-linear
• B. bilateral
• C. linear
• D. none of the above

Explanation: A diode's current does not vary proportionally with voltage, as shown by its curved V-I characteristic.

• A. linear
• B. active
• C. nonlinear
• D. passive

Explanation: A straight-line voltage-current characteristic gives a constant ratio of voltage to current, so the device obeys Ohm’s law and is linear.

• A. the same as
• B. lower than
• C. more than
• D. none of the above

Explanation: A crystal diode generally has a lower peak inverse voltage rating than an equivalent vacuum diode because its semiconductor junction is…

• A. minority carriers
• B. majority carriers
• C. junction capacitance
• D. none of the above

Explanation: Reverse leakage current is produced by thermally generated minority carriers crossing the reverse-biased junction.

• A. kA
• B. mA
• C. μA
• D. A

Explanation: A diode’s reverse leakage current is normally very small, commonly expressed in microamperes in basic device theory.

• A. heavily
• B. moderately
• C. lightly
• D. none of the above

Explanation: The transistor base is lightly doped and made very thin so that most carriers injected from the emitter can pass through it and reach the…

• A. a reverse bias
• B. a wide depletion layer
• C. low resistance
• D. none of the above

Explanation: In normal transistor operation, the base-emitter junction is forward biased, producing a narrow depletion region and low junction…

• A. 0o
• B. 180o
• C. 90o
• D. 270o

Explanation: A common-emitter amplifier reverses the output voltage relative to the input, giving a phase difference of 180°.

• A. 1800
• B. 00
• C. 900
• D. 2700

Explanation: The common-collector, or emitter-follower, configuration is non-inverting, so its output voltage is essentially in phase with its input…

• A. Is decreased
• B. Is increased
• C. Remains the same
• D. None of the above

Explanation: For the usual voltage-series negative-feedback amplifier, the feedback signal is applied in series with the input, increasing the input…

• A. Current gain
• B. Impedance matching
• C. Voltage gain
• D. None of the above

Explanation: An emitter follower has nearly unity voltage gain but provides substantial current gain and a high-input, low-output impedance…

• A. Is increased
• B. Is decreased
• C. Remains the same
• D. Insufficient data

Explanation: Negative feedback reduces the amplifier's gain but extends its frequency range, so the bandwidth increases.

• A. electron current in the emitter
• B. electron current in the collector
• C. hole current in the emitter
• D. donor ion current

Explanation: The transistor arrow follows the direction of conventional emitter current, conventionally associated with hole-current direction.

• A. Voltage feedback
• B. Current feedback
• C. Both voltage and current feedback
• D. None of the above

Explanation: An emitter follower uses voltage-series feedback: part of the output voltage is fed back in series opposition to the input.