A transistor is used in common-emitter mode in an amplifier circuit. It is found that when a signal of `20mV` is added to the base-emitter voltage, the base current changes by `20muA` and collector current changes by `1.5mA`. Determine the factor beta, input resistance `R_(i)`, the transconductance and voltage gain, Given load resistance `R_(L)=6kOmega`.

Explanation

Here `DeltaV_(i)=20xx10^(-3)V, DeltaI_(b)=20xx10^(-6)A`,
`DeltaI_(c)=1.5xx10^(-3)A, R_(0)=6xx1000Omega`.
`beta_(a.c.)=(DeltaI_c)/(DeltaI_b)=(1.5xx10^(-3))/(20xx10^(-6))=75`
`R_(i)=(DeltaV_(i))/(DeltaI_b)=(20xx10^(3))/(20xx10^(6))=1000Omega`
Transcondutance `=(DeltaI_c)/(DeltaV_(i))=(1.5xx10^(3))/(20xx10^(-3))=0.075 S`
Voltage gain `=beta_(a.c.)xxR_(0)//R_(i)
=75xx6000//1000=450`