In a silicon transistor, base current is changed by `20muA`. This result in a change of `0.02V` in base-emitter voltage and a change of `2 mA` in the collector current.
Find the input resistance, `beta_(a.c.)` and transconductance of the transistor.
The transistor is used as an amplifier with the load resistance `5k Omega`. What is the voltage gain of the amplifier?

Explanation

`R_(i)=(DeltaV_(i))/(DeltaI_b)=(0.02V)/(20muA)=1000Omega=1kOmega`
`beta_(a.c.)=(DeltaI_c)/(DeltaI_b)=(2mA)/(20muA)=100`
`g_(m)=(DeltaI_c)/(DeltaV_(i))=(2mA)/(0.02V)=(2xx10^(-3))/0.02=0.1Omega^(-1)`
`A_(V)=beta_(a.c.)R_(0)/R_(i)=100xx(5kOmega)/(1kOmega)=500`