Free Electronics and Devices MCQs with Answers

• A. reverse
• B. forward
• C. reverse as well as forward
• D. none of the above

Explanation: The JFET gate-channel junction is normally reverse biased, so its gate current is nearly zero and its input resistance is very high.

• A. cathode, anode, grid
• B. emitter, base, collector
• C. source, gate, drain
• D. none of the above

Explanation: The three terminals of a JFET are the source, gate, and drain. Emitter, base, and collector belong to a BJT, while anode, cathode, and…

• A. decreases
• B. increases
• C. remains constant
• D. none of the above

Explanation: At pinch-off, the JFET enters its saturation or constant-current region, where further increases in drain voltage produce nearly no…

• A. unipolar
• B. bipolar
• C. unijunction
• D. none of the above

Explanation: A JFET is called unipolar because conduction is produced by only one type of majority carrier, either electrons or holes.

• A. equal to
• B. less than
• C. more than
• D. none of the above

Explanation: Because the reverse-biased JFET gate junction draws almost no current, its input impedance is much higher than that of an ordinary BJT.

• A. Receiving antenna
• B. Radio transmitter
• C. Radio receiver
• D. Television receiver

Explanation: A clamping circuit shifts the entire waveform upward or downward without substantially changing its shape, a function commonly used in…

• A. ICBO
• B. ICEO
• C. (ß + 1) ICEO
• D. IC(sat)

Explanation: In CE cutoff, the base is open in the leakage-current model, so the collector current is the collector-to-emitter leakage current, ICEO.

• A. Off
• B. Saturation
• C. Active
• D. None of the above

Explanation: For amplification, the transistor must remain in the active region, where collector current varies approximately with base current and the…

• A. Negative
• B. Positive
• C. Both positive and negative
• D. None of the above

Explanation: A negative clipper is designed to remove or limit the negative half-cycles of an input waveform while allowing the positive half-cycles to…

• A. Negative
• B. 100 % positive
• C. Both positive and negative
• D. None of the above

Explanation: A multivibrator uses regenerative, or positive, feedback so that a small change is reinforced and the circuit rapidly switches between…

• A. Two stable states
• B. One stable state
• C. No stable state
• D. None of the above

Explanation: A bistable multivibrator has two stable states and remains in either state until an external trigger changes it.

• A. 5 times greater than
• B. 5 times smaller than
• C. Equal to
• D. At least 10 times greater than

Explanation: An RC integrator requires the capacitor voltage to change slowly compared with the input waveform, so the time constant must be much…

• A. No stable state
• B. One stable state
• C. Two stable states
• D. None of the above

Explanation: A monostable multivibrator has one stable state and one temporary state.

• A. Negative
• B. Positive
• C. Both positive and negative
• D. None of the above

Explanation: A positive clipper removes or limits the positive half-cycles while allowing the negative half-cycles to pass.

• A. Monostable
• B. Bistable
• C. Astable
• D. None of the above

Explanation: An astable multivibrator has no stable state and continuously switches between its two quasi-stable states.

• A. VCC
• B. 0
• C. VCC/2
• D. VCC/3

Explanation: In the usual common-emitter transistor switch, cutoff makes collector current essentially zero, so there is no voltage drop across the…

• A. 20 V
• B. 10 V
• C. 0 V
• D. None of the above

Explanation: A differentiator responds to changes in voltage, and a steady DC level has zero rate of change after the switching transient.

• A. Sine wave
• B. Sharp narrow pulses
• C. Rectangular wave
• D. Triangular wave

Explanation: A differentiator produces a large pulse whenever the input changes rapidly.

• A. Square
• B. Triangular
• C. Sine
• D. Rectangular

Explanation: The ramp portion of a sawtooth has an approximately constant slope, so differentiation gives a constant level; the rapid reset gives a…

• A. One stable state
• B. Two stable states
• C. No stable state
• D. None of the above

Explanation: An astable multivibrator has no stable state, so it continuously alternates between its two temporary states.