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

Current gain In common base mode `alpha=(I_(C))/(I_(E))=0.98` Voltage gain `A_(V)=alpha(R_(L))/(R_("in"))=0.98 xx (5xx 10^(3))/(70)implies A_(V)=70`
Power gain `A_(P)=a^(2)(R_(L))/(R_("in"))=(0.98)^(2)xx(5 xx 10^(3))/(70)`
`implies A_(V)=70`
Power gain ,
`A_(P)=a^(2)(R_(L))/(R_("in"))=(0.98)^(2)xx(5 xx 10^(3))/(70)`
`implies A_(V)=68.6`