Target Exam

CUET

Subject

Physics

Chapter

Current Electricity

Question:

In a transistor, the change produced in collector current is 3 mA, when the base current is changed by 60 μA. This transistor is used as a common emitter amplifier with a load resistance of 5 KΩ. The input resistance of this silicon transistor is 50 Ω. The voltage gain of the amplifier is:

Options:

2000

500

200

5000

Correct Answer:

5000

Explanation:

The correct answer is Option (4) → 5000

To calculate the voltage gain of an amplifier,

$A_v=\frac{ΔV_{out}}{ΔV_{in}}=\frac{ΔI_C.R_L}{ΔI_B.r_{in}}$

$∴A_v=\frac{(3×10^{-3}A)(5000Ω)}{(60×10^{-6}A).50Ω}$

$=\frac{15V}{3mV}=5000$