CBT Electronic & Electrical Fundamentals 3

Question 1

In a common-emitter BJT amplifier, what is the phase relationship between input and output signals?

Accepted Answer

180° phase shift

Answer

A common-emitter amplifier inverts the signal, producing a 180° phase shift between input and output.

Question 2

What is the time constant of a circuit with a 10kΩ resistor and a 100μF capacitor?

Accepted Answer

1 second

Answer

The RC time constant τ = R × C = 10,000Ω × 0.0001F = 1 second.

Question 3

What does the term 'dBm' represent in RF and broadcast engineering?

Accepted Answer

Decibels relative to 1 milliwatt

Answer

dBm is a unit of power expressed in decibels relative to a reference of 1 milliwatt.

Question 4

In a full-wave rectifier with a center-tapped transformer, how many diodes are required?

Accepted Answer

Two

Answer

A center-tapped full-wave rectifier uses two diodes, one for each half of the AC cycle from the center-tapped secondary.

Question 5

What is the voltage gain of an op-amp inverting amplifier with a feedback resistor of 100kΩ and an input resistor of 10kΩ?

Accepted Answer

-10

Answer

The gain of an inverting op-amp amplifier is -Rf/Rin = -100kΩ/10kΩ = -10.

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