(a) For given transistor circuit, the base current is `10muA` and the collector current is 5.2 mA. Can this transistor circuit be used as an amplifier. Your answer must be supported with proper explanation.
(b). For a common emitter amplifier, current gain is 69. if the emitter current is 7 mA then calculate the base current and collector current.

Explanation

(a). To find the given circuit can be used as an amplifier, we find `V_(BE)` and `V_(CE)`
`V_(BE)=V_(C C)-1I_(B)R_(B)`
`=5.5-10xx10^(-6)xx500xx10^(3)`
`=0.5 V`
`V_(CE)=V_(C)-1I_(C)R_(C)`
`=5.5-5.2xx10^(-3)xx1xx10^(3)=0.3V`
As both the emitter-base junction and collecter emitter junction are forward bias (both have positive sign), it can't be used as an amplifier,
Current gain `beta=(I_(C))/(I_(B))=69` ..(i)
and `I_(E)=I_(B)+I_(C)=7mA` ..(ii)
From Eqs. (i) and (ii) we get
`69=(I_(C))/(7-I_(C))`
`impliesI_(C)=6.9mA`
Substituting the value fo `I_(C)` in Eq. (ii), we obtain the value of `I_(B)=0.1mA`.