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A transistor is used in Common-emitter m...

A transistor is used in Common-emitter mode in an amplifier circuits. When a signal of 20 mV is added to the base-emitter voltage, the base current changes by `40 muA` and the collector current changes by 2mA. The load resistance is `5 kOmega` then the voltage gain is

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(i)`beta =(Delta I_(c))/(Delta I_(B))=(2mA)/(20muA)=100`(ii) The input resistance `R_(BE)=(Delta V_(BE))/(Delta I_(B)) =(20mA)/(20mu A)=1 k Omega`(iii)Transconductance, =`(Delta I_(c))/(Delta V_(BE))= (2mA)/(20mv)`=o.1mho.(iv)The cahnge in output voltage is `R_(L) Delta I_(c)=(5k Omega)(2mA)=10V`,The applied signal voltage =20mV.Thus, the voltage gain is `(10V)/(20mv)=500`
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