A change of `0.2mA` in the base current cause a change of `5mA` in the collector current for a common emitter amplifier. (i) Find the a.c. current gain of the transistor (ii) If the input resistance is `2kOmega` and its voltage gain is 75. Calculate the load resistance used in the circuit.

Explanation

Here, `DeltaI_(B)=0.2mA=0.2xx10^(-3)A=2xx10^(-4)A`
`DeltaI_(C)=5mA=5xx10^(-3)A`
(i) `beta_(ac)=(DeltaI)/(DeltaI)=(5xx10^(-3))/(2xx10^(-4))=25`
(ii)`A_(V)=betaR_(L)/R_(i)` or `R_(L)=(A_(V)xxR_(i))/beta=(75xx2kOmega)/25=6KOmega`