Free Electronics and Devices MCQs with Answers

• A. the edge of the depletion region on the p-side
• B. the edge of the depletion region on the n-side
• C. the p-n junction
• D. the center of the depletion region on the n-side

Explanation: Under reverse bias, the electric field rises from zero at the depletion-region edges to its maximum at the p-n junction, where the…

• A. affects the difference mode gain Ad
• B. affects the common mode gain Ac
• C. affects both Ad and Ac
• D. does not effect either Ad and Ac

Explanation: Changing the emitter or tail resistance mainly changes the common-mode gain because common-mode currents flow through this resistance.

• A. the mobility decreases
• B. the transconductance increases
• C. the drain current increases
• D. none of the above

Explanation: As FET temperature rises, carrier mobility decreases, reducing drain current for a given gate bias.

• A. forward
• B. reverse
• C. both forward and reverse
• D. none of the above

Explanation: A zener diode is normally operated in reverse bias, where its controlled breakdown characteristic provides voltage regulation.

• A. undefined
• B. sharp
• C. zero
• D. none of the above

Explanation: A zener diode is manufactured to enter breakdown at a specified, sharply defined voltage.

• A. properly reverse bias the zener
• B. protect the zener
• C. properly forward bias the zener
• D. none of the above

Explanation: The series resistor limits the current through the zener when it operates in breakdown, preventing excessive dissipation and damage.

• A. junction capacitance
• B. charge storage capacitance
• C. depletion capacitance
• D. channel length modulation

Explanation: Junction, depletion, and charge-storage capacitances are associated with p-n junction behavior.

• A. constant voltage
• B. constant current
• C. constant resistance
• D. none of the above

Explanation: In breakdown, a zener diode holds its voltage nearly constant over a range of current, so it is modeled approximately as a…

• A. a non-linear
• B. a linear
• C. an amplifying
• D. none of the above

Explanation: A zener diode has a nonlinear voltage-current characteristic, especially around its breakdown region.

• A. ICEO
• B. ICBO
• C. IC
• D. (1 - a ) IB

Explanation: Starting with I_C = βI_B + I_CEO and β = α/(1 − α), the relation becomes I_C = [α/(1 − α)]I_B + I_CEO.

• A. ICBO
• B. IC
• C. ICEO
• D. aIE

Explanation: For a transistor in common-emitter form, collector current is I_C = βI_B + I_CEO, where I_CEO is the collector-emitter leakage current…

• A. common emitter
• B. common collector
• C. common base
• D. none of the above

Explanation: The common-base configuration has very high output resistance because its collector output characteristic is nearly flat.

• A. paper capacitor
• B. air capacitor
• C. mica capacitor
• D. electrolytic capacitor

Explanation: Paper capacitors are commonly used as high-voltage filter capacitors because they withstand high working voltages and provide suitable…

• A. IB
• B. ICEO
• C. ICBO
• D. ßIB

Explanation: The common-base transistor relation is I_C = αI_E + I_CBO, where I_CBO is the collector-to-base leakage current with the emitter open.

• A. the diode conducts poorly
• B. the diode is destroyed
• C. the diode behaves like a zener diode
• D. none of the above

Explanation: Exceeding a diode's peak inverse voltage causes reverse-breakdown current, which can overheat and permanently damage the junction.

• A. acceptor ions
• B. donor ions
• C. free electrons
• D. holes

Explanation: A PNP transistor has holes as its majority charge carriers, supplied mainly by the p-type emitter.

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

Explanation: The collector is moderately doped so it can withstand a relatively high reverse-bias voltage while still collecting carriers efficiently.

• A. paper capacitor
• B. mica capacitor
• C. electrolytic capacitor
• D. air capacitor

Explanation: A 10 V power supply commonly uses an electrolytic capacitor because it provides large capacitance for smoothing rectified voltage and is…

• A. free electrons
• B. holes
• C. donor ions
• D. acceptor ions

Explanation: In an NPN transistor, electrons are the majority carriers because the emitter and collector are n-type, while holes are the minority…

• A. high
• B. low
• C. very high
• D. almost zero

Explanation: A transistor's input impedance is generally low to moderate, especially compared with a field-effect transistor, because its input…