A transistor is used as an amplifier in `CB` mode with a load resistance of `5 k Omega` the current gain of amplifier is `0.98` and the input resistance is `70 Omega`, the voltage gain and power gain respectively are

Options

A. `70,68.6`
B. `80,75.6`
C. `60,66.6`
D. `90,96.6`

Answer

A

Explanation

In common base mode `alpha=0.98, R=5 kOmega,R_(i n)=70 Omega`
`:.` Voltage gain `A_(v)=alphaxxR/(R_(i n)) =0.98xx(5xx10^(3))/70=70`
power gain =Current gain xVoltage gain
`=0.98xx70=68.6`