Question

If IC = 50 mA and IE = 52 mA, calculate the current gain of the transistor

Answer 1

There are two configuration mainly for transistor current amplifier.

1) Common emitter: In common emitter the current gain $(\beta) =\frac{I_C}{I_B}$

We have $I_E=I_B+I_C$

There fore $I_B=I_E-I_C=52-50=2mA$

Hence $\beta=\frac{50}{2}=25$

2)Common base: In common base current gain$(\alpha) =\frac{I_C}{I_E}=\frac{50}{52}=0.96$

Generally $\alpha$ is close to one. Common emitter is more popular and widely used due to it's large gain.