When the transistor is used as an amplifier

Explanation

`therefore E_(n)=(Ze^(2))/(8piepsilon_(0)r)`

(i) Collector end is reverse biased and base - emitter ends forward - biased
(ii) A small variation in the base current produces a large variation in the collector current with a phase difference of `180^(@)` between them, without altering the input frequency. This is the basis of an amplifier circuit. 1
(iii) Power gain of the amplifier in CE mode is given by,
`P_("gain")=(P_("output"))/(P_("input"))`
`=beta^(2)(R_(0))/(R_(i))`
where current gain `beta =(I_(0))/(I_(1))=(I_(c ))/(I_(B))`

(iv) The input and output voltages are as shown in the figure above.