The input resistance of a common emitter transistor amplifer, if the output resistance is `500 K Omega`, the current gain `alpha = 0.98` and power gain is `6.0625 xx 10^(6)`, is

Options

A. `100 Omega`
B. `300 Omega`
C. `198 Omega`
D. `400 Omega`

Answer

C

Explanation

Votalge gain `=A_(V)=beta(R_(2))/(R_(1))`
Also, current gain `beta=(alpha)/(1-alpha)=0.98/(1-0.98)=49`
`A_(V)=(49)[(500xx10^(3))/(R_(1))]`
Power gain `=6.0625xx10^(6)=49xx[(500xx10^(3))/(R_(1))]xx49`
`:. R_(1)=198 Omega`