Question

In an n-p-n transistor circuit, the collector current is 9 mA. If 90% of the electrons emitter reach the collector, find the base current and emitter current.
A. `alpha =0.9, beta=9.0`
B. the base current is 10 mA
C. the emitter current is 1 mA
D. `alpha=9.0, beta=0.9`

Answer 1

Correct Answer - A
Let `I_(e)` be the emitter current.
`therefore (90)/(100)xx I_(e) = I_(c) rArr I_(e) =(100I_(c))/(90)=(10)/(9)I_(c)`
`therefore alpha=(I_(c))/(I_(e))=(9)/(10)=0.9`
`and beta=(I_(c))/(I_(b))=(I_(c))/(I_(e)-I_(c))=(1)/((I_(e))/(I_(c))-1)=(1)/((10)/(9)-1)=(9)/(1)=9`