Question

For a transistor amplifier, the voltage gain (A) remains constant for all frequencies (B) is high at high and low frequencies and constant in the mid-frequency range (C) is low at high and low frequencies and constant in the mid-frequency range (D) None of the above

Short answer

In a transistor amplifier, the voltage gain is low at high and low frequencies and constant in the mid-frequency range due to the effects of internal capacitances and external components in the circuit. Therefore, the correct answer is (C).

Step-by-step solution

Understand the frequency response of a transistor amplifier

A transistor amplifier's frequency response refers to the relationship between the voltage gain and the frequency of the input signal. The frequency response is influenced by various factors, including the internal capacitances of the transistor and the external components in the circuit.

Consider the low-frequency range

At low frequencies, the capacitive reactance of coupling and bypass capacitors in the circuit becomes high. This causes a reduction in gain as the input signal gets attenuated.

Consider the mid-frequency range

In the mid-frequency range, the capacitive reactance of coupling and bypass capacitors is low, and the gain remains constant and at its maximum.

Consider the high-frequency range

At high frequencies, a transistor amplifier's gain decreases due to the Miller effect and internal capacitances of the transistor. The increasing capacitive coupling between input and output causes a loss in the gain.

Choose the correct option

Based on our understanding of the transistor amplifier's frequency response, we can now select the correct answer: - (A) is incorrect because the voltage gain does not remain constant for all frequencies. - (B) is incorrect because the gain does not remain high at high and low frequencies. - (C) is the correct choice, as the gain is low at high and low frequencies and constant in the mid-frequency range. - (D) is incorrect as the correct answer is (C).