For a common emitter amplifier , current gain is 70 . If the emitter is 8.8 mA , calculate the collector and base current . Also calculate current gain , when transistor is worked on common base amplifier .

Explanation

Data supplied ,
`beta = 70 , I_(E) = 8.8 mA , beta = (I_(C))/(I_(B))`
`I_(C) = beta I_(B) = 70 xx I_B`
`I_(E) = I_(C) + I_(B) = 70 I_(B) + I_(B)`
`I_(B) = (8.8)/(71) = 0.124 mA`
`I_(C) = beta I_(E) = 70 xx 0.124 = 8.68` mA
`beta = (alpha)/(1 - alpha)`
`70 = (alpha)/(1 - alpha)`
`alpha = (70)/(71) = 0.986`