The current gain for a transistor working as a common-base amplifier is `0.96`. If the emitter current is `7.2 mA`, the base current will be

Options

A. `0.45 mA`
B. `0.29 mA`
C. `093 mA`
D. zero

Answer

B

Explanation

Here, `alpha=0.96,I_(e)=7.2 mA`
`alpha=(I_(c))/(I_(e)) or I_(c)= alphaI_(e)`
`=0.96xx7.2= 6.91 mA`
Now, `I_(e)=I_(c)+I_(b)`
`rArr I_(b)=-I_(e)-I_(c)`
`=-7.2-6.91=0.29 mA`