`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
`Delta I_B = 40 mu A = 40 xx 10^(-6) A `
`Delta I_C = 2mA = 2 xx 10^(-3) A `
` Delta V_(BE ) = 0.04 ` volt `R_L = 6 k Omega = 6 xx 10^2 Omega `
(i) Input Resistance,
`R_("in") = (Delta V_(BE ))/( Delta I_(B )) = ( 0.04 ) /( 40 xx 10^(-6) ) = 10^3 Omega 1 k Omega `
(ii) Current amplification factor,
` beta = (Delta I_C )/(Delta I_B) = ( 2 xx 10^(-3))/( 40 xx 10^(-6)) = 50`
(iii) Voltage gain in common-emitter configuration.
` A_u = beta (R_L)/(R_("imp"))=50 xx(6 xx 10^3)/( 1 xx 10^3 ) = 300`