Question

In common emitter mode of transistor, the d.c. current gain is 20, the emitter current is 7 mA. The collector current is ______.

Options

• 16/3 mA

• 20/3 mA

• 8/3 mA

• 13/3 mA

Answer 1

In common emitter mode of transistor, the d.c. current gain is 20, the emitter current is 7 mA. The collector current is 20/3 mA.

Explanation:

`beta=I_"C"/I_"B"=20`

`I_"C"/(I_"E"-I_"C")=20`

`(I_"E"-I_"C")/I_"C"=1/20`

`I_"E"/I_"C"-1=1/20`

`I_"E"/I_"C"=1/20+1=21/20`

`I_"C"=20/21xx7=20/3  "mA"`