Free Electronics and Devices MCQs with Answers

• A. Biasing circuit
• B. Bias battery
• C. Diode
• D. None of the above

Explanation: Transistor biasing is normally established using a biasing circuit containing suitable resistors and a supply arrangement.

• A. Proper direct current
• B. Proper alternating current
• C. The base current small
• D. Collector current small

Explanation: Biasing establishes the transistor’s required quiescent or zero-signal DC currents and voltages so the signal can be amplified without…

• A. Be zero
• B. Be 0.01 V
• C. Not fall below 0.7 V
• D. Be between 0 V and 0.1 V

Explanation: A silicon base-emitter junction needs about 0.7 V forward bias to conduct properly in the active region.

• A. 4
• B. 1
• C. 3
• D. More than 10

Explanation: Small-signal amplifier stages commonly use a quiescent collector current of about 1 mA, providing suitable amplification while keeping…

• A. Operating point
• B. Current gain
• C. Voltage gain
• D. None of the above

Explanation: The intersection of the DC load line and AC load line gives the quiescent operating point, also called the Q-point.

• A. Not fall below 1 V
• B. Be zero
• C. Be 0.2 V
• D. None of the above

Explanation: Keeping VCE above approximately 1 V prevents the transistor from entering saturation during signal variations, allowing faithful…

• A. Values of IC and VCE when signal is applied
• B. The magnitude of signal
• C. Zero signal values of IC and VCE
• D. None of the above

Explanation: The operating point is defined by the quiescent, or zero-signal, values of collector current IC and collector-emitter voltage VCE.

• A. a.c
• B. d.c
• C. both a.c. and d.c
• D. none of the above

Explanation: Transistor biasing sets the DC voltages and currents that establish the operating point.

• A. Proper forward bias
• B. Proper reverse bias
• C. Very small size
• D. None of the above

Explanation: For a transistor to operate in the active region, its collector-base junction must be reverse biased.

• A. Decrease in the base current
• B. Unfaithful amplification
• C. Excessive collector bias
• D. None of the above

Explanation: Without biasing, the transistor may remain in cutoff or enter saturation during part of the signal cycle, causing distortion.

• A. A few free electrons
• B. Many holes
• C. Many free electrons
• D. No holes or free electrons

Explanation: At absolute zero, thermal energy is insufficient to create electron-hole pairs in an ideal intrinsic semiconductor.

• A. O
• B. kO
• C. MO
• D. None of the above

Explanation: A reverse-biased junction permits only a tiny leakage current, so its opposition to current is very high, typically of the order of…

• A. Very narrow depletion layer
• B. Almost no current
• C. Very low resistance
• D. Large current flow

Explanation: Reverse bias widens the depletion region and strongly restricts majority-carrier flow, leaving only a very small leakage current.

• A. 5 V
• B. 3 V
• C. Zero
• D. 0.3 V

Explanation: The barrier voltage of a silicon junction is about 0.7 V, while germanium has the lower value of approximately 0.3 V.

• A. Diffusion
• B. Pressure
• C. Ionisation
• D. None of the above

Explanation: Thermal agitation gives carriers random motion, and their net movement from a region of higher concentration to lower concentration is…

• A. Repel each other
• B. Attract each other
• C. Have no effect on each other
• D. None of the above

Explanation: An electron carries negative charge and a hole behaves as a positive charge, so their electrostatic force is attractive.

• A. +ve terminal to p and -ve terminal to n
• B. -ve terminal to p and +ve terminal to n
• C. -ve terminal to p and -ve terminal to n
• D. None of the above

Explanation: Forward bias connects the positive terminal to the p-side and the negative terminal to the n-side, reducing the depletion barrier.

• A. Acceptor ions
• B. Holes and electrons
• C. Donor ions
• D. None of the above

Explanation: Near the junction, electrons and holes recombine, leaving a depletion region almost free of mobile carriers.

• A. Controlled switch
• B. Bidirectional switch
• C. Unidirectional switch
• D. None of the above

Explanation: A pn junction conducts readily in forward bias but blocks current in reverse bias, so it behaves like a unidirectional switch.

• A. Equals the number of holes
• B. Is greater than the number of holes
• C. Is less than the number of holes
• D. None of the above

Explanation: In an intrinsic semiconductor, electron-hole pairs are generated together, so every free electron is accompanied by a hole.