Question

A common base transistor amplifier has an input resistance of 20Ω and output resistance of 100kΩ. If a signal of 400mV is applied between emitter and base, find the voltage amplification. Assume αac to be one.

(a) 20

(b) 50

(c) 30

(d) 25

I have been asked this question by my college director while I was bunking the class.

I'm obligated to ask this question of The Transistor as an Amplifier topic in section Transistor Characteristics of Electronic Devices & Circuits

Answer 1

Right answer is (b) 50

Explanation: IE = V/R=400M/20=20mA

IC=αIE= 1*20mA=20mA. VO=IC*RL=20m*1k=20V

Amplification, A= VO/signal voltage=20V/400m=50.