Question

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
A. `0.42 mA`
B. `0.49 mA`
C. `0.35 mA`
D. `0.29 mA`

Answer 1

Correct Answer - D
Current gain of transistor is
`alpha=(DeltaI_(C))/(Deltai_(E))`
Where `Deltai_(C)` is change in collector current, and `Deltai_(E)` is change in emitter current.
Given, `alpha=0.96,Deltai_(E)=7.2`,
`Deltai_(C)=0.96xx7.2=6.91 mA`
Also `Deltai_(E)=Deltai_(C)+Deltai_(B)`
`:. Deltai_(B)=Deltai_(E)+Deltai_(C)=7.2-6.91=0.29 mA`