Which parameter is most important for selecting a heat sink for a power transistor?

The correct answer is B: Thermal resistance (θJA). Thermal resistance θJA (junction to ambient) determines how effectively heat is dissipated. Lower θJA values indicate better heat dissipation capability, essential for power dissipation calculations: Tj = Ta + (P × θJA).

A power amplifier delivers 100 W to a 8 Ω load. What is the RMS output voltage? (Assuming pure resistive load)

The correct answer is A: 28.3 V. P = V²/R → V = √(P×R) = √(100×8) = √800 ≈ 28.3 V RMS.

In VHDL, what does the 'rising_edge' function detect?

The correct answer is B: Transition from 0 to 1. 'rising_edge' detects a transition from LOW (0) to HIGH (1) on a signal, commonly used in synchronous designs to trigger actions on positive clock edges

In a silicon p-n junction diode at room temperature (T = 300K), the thermal voltage (VT) is approximately:

The correct answer is A: 26 mV. Thermal voltage VT = kT/q, where k = 1.38×10⁻²³ J/K, T = 300K, q = 1.6×10⁻¹⁹ C. VT ≈ 26 mV at room temperature, a fundamental parameter in semiconductor device physics.

Which of the following logic gates has an output of 1 only when both inputs are different?

The correct answer is A: XOR gate. XOR (Exclusive OR) produces 1 when inputs are different and 0 when they are same.

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Electronics (ECE)

Analog/digital electronics, communication

135 Q 4 Topics Take Mock Test

Difficulty: All Easy Medium Hard 131–135 of 135

Topics in Electronics (ECE)

All Electronic Devices 100 Digital Electronics 100 Analog Circuits 100 Signals & Systems 100

Q.131 Easy Electronic Devices

What is the relationship between collector current (Ic) and base current (Ib) in a BJT?

A Ic = Ib × β (beta)

B Ic = Ib / β

C Ic = Ib + β

D Ic = β / Ib

Correct Answer: A. Ic = Ib × β (beta)

EXPLANATION

In BJT, the current gain (beta or hFE) is defined as the ratio of collector current to base current: β = Ic/Ib, so Ic = Ib × β. Beta typically ranges from 50 to 500 for most transistors.

Test

Q.132 Easy Electronic Devices

In a BJT (Bipolar Junction Transistor), what are the three regions of operation?

A Saturation, Amplification, Cutoff

B Saturation, Active, Cutoff

C Conduction, Amplification, Blocking

D Forward, Reverse, Neutral

Correct Answer: B. Saturation, Active, Cutoff

EXPLANATION

BJT operates in three distinct regions: Active region (linear amplification with both junctions forward biased), Saturation (both junctions forward biased, acts as switch ON), and Cutoff (both junctions reverse biased, acts as switch OFF).

Test

Q.133 Easy Electronic Devices

Which of the following is NOT a characteristic of a Zener diode?

A Operates in reverse bias region

B Used for voltage regulation

C Has high forward resistance

D Conducts heavily in forward bias like normal diodes

Correct Answer: C. Has high forward resistance

EXPLANATION

Zener diodes have low forward resistance (like normal diodes in forward bias) but the unique property is controlled reverse breakdown at a specific voltage for regulation purposes.

Test

Q.134 Easy Electronic Devices

The barrier potential of a silicon PN junction at room temperature is approximately:

A 0.3 V

B 0.7 V

C 1.4 V

D 2.0 V

Correct Answer: B. 0.7 V

EXPLANATION

Silicon PN junctions have a built-in barrier potential of approximately 0.7 V at room temperature (25°C), while germanium junctions are around 0.3 V.

Test

Q.135 Easy Electronic Devices

What is the primary function of a PN junction diode?

A To allow current flow in both directions equally

B To allow current flow preferentially in one direction

C To amplify electrical signals

D To store electrical charge indefinitely

Correct Answer: B. To allow current flow preferentially in one direction

EXPLANATION

A PN junction diode exhibits rectification property, allowing current to flow easily in the forward direction (low resistance) and blocking it in the reverse direction (high resistance).

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