`AP-N-P` transistor is used in common-emitter mode in an amplifier circuit. A change of `40muA` in the base current brings a change of 2 mA in collector current and 0.04 V in base-emitter voltage. Find the , (1) input resistance `(R_("input"))` and
(2). the base current amplification factor `(beta)`.
If a load of `6kOmega` is used then also find the voltage gain of the amplifier

Explanation

Given `DeltaI_(B)=40muA=40xx10^(-6)A`
`DeltaI_(C)=2mA=2xx10^(-3)A`
`DeltaV_(BE)=0.04" volt, "R_(L)=6kOmega=6xx10^(3)Omega`
(i) Input Resistance,
`R_("in")=(DeltaV_(BE))/(DeltaI_(B))=(0.04)/(40xx10^(-6))=10^(3)Omega=1kOmega`
(ii) Current amplification factor,
`beta=(DeltaI_(C))/(DeltaI_(B))=(2xx10^(-3))/(40xx10^(-6))=50`
(iii) Voltage gain in common - emitter configuration.
`A_(u)=beta(R_(L))/(R_("lmp"))=50xx(6xx10^(3))/(1xx10^(3))=300`