Question

An n - p- n transistor is connected in common - emitter configuraration in which collector supply is 8 V and the voltage drop across the load resistance of ` 800 Omega ` connected in the collector circuit is 0.8 V . If current amplification factor is 25 , determine collector - emitter voltage and base current . If the internal resistance of the transistor is ` 200 Omega ` , calculate the voltage gain and the power gain.

Answer 1

Correct Answer - A::B::C::D
The corresponding circuit is shown in figure .
Voltage across ` R_L =i_(c )R_(L)= 0.8 V ` (given )
` :. i_c = 0.8 /R_L = 0.8 / 800 A = 1 mA `
Further it is given that,
` beta = 25 = i_c / i_b `
` :. i_b = i_c / 25 = 40 mu A `
Collector - Emitter Voltage `(V_(CE)) `
Applying Kirchhoffs second law in emitter - collector circuit , we have
` V_(CE) = (8-0.8) V = 7.2 V ` .
Voltage gain ` ( A_V) `
Voltage gain,` A_V = beta (R_"out" / R_"in") `
or ` A_V = 25 (800 / 200) = 100 `
Power gain ` Power gain ` = beta^(2) (R_"out" / R_"in") = (25)^(2) (800 / 200) = 2500 `