Question

In CB configuration, the value of α=0.98A. A voltage drop of 4.9V is obtained across the resistor of 5KΩ when connected in collector circuit. Find the base current.

(a) 0.01mA

(b) 0.07mA

(c) 0.02mA

(d) 0.05mA

The question was asked by my college director while I was bunking the class.

My question is based upon The AC Analysis of a Small-Signal Low-Frequency Common Emitter Transistor. topic in division Small-Signal Low-Frequency AC models of Transistors of Electronic Devices & Circuits

Answer 1

Right answer is (c) 0.02mA

To explain: Here, IC=4.9/5K=0.98mA

α = IC/IE .So,

IE=IC/α=0.98/0.98=1mA.

IB=IE-IC=1-0.98=0.02mA.