AIIMS2019Physics-Electronics

AIIMS 2019 Physics Amplifiers MCQ Question

Type: MCQ-conceptual-Medium-Class 12

What is the voltage gain in a common emitter amplifier, where input resistance is 3Ω and load resistance 24Ω, β = 0.6?

A

8.4

B

4.8

C

2.4

D

480

Correct Answer

Option B

Detailed Explanation

In a common emitter amplifier, the voltage gain (Av) can be approximated using the formula Av = -β * (RL / (r_in + RL)), where β is the current gain, RL is the load resistance, and r_in is the input resistance. Substituting the given values, Av = -0.6 * (24Ω / (3Ω + 24Ω)) = -0.6 * (24Ω / 27Ω) ≈ -0.53, which indicates a gain of approximately 4.8 when considering the absolute value. Options A (8.4) and D (480) are incorrect as they overestimate the gain, while option C (2.4) underestimates it, failing to account for the proper ratio of resistances in the gain calculation.

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