Question

In a transistor when base-emitter voltage is changed from `0.6 V` to `0.8 V`, the change in base current is `500 muA` to the change in collector current is `10 mA` to `40 mA`, when the collector-emitter voltage is kept constant at `2 V`. Find input impendance forward current ratio:

Answer 1

Here `DeltaV_(be)=0.8-0.6=0.2V`
`DeltaI_(b)=700-500=200 muA=200xx10^(-6)A`
`DeltaI_(c)=40-10=30mA=30xx10^(-3)A`
Input impedance `(h_(ie))=((DeltaV_(be))/(DeltaI_b))_(VCE is constant) :. h_(ie)=(0.2)/(200xx10^(-6))=10^(3)Omega`
Forward current ratio `(h_(fe))=((DeltaV_(be))/(DeltaI_b))_(VCE is constant)`
`:. h_(fe)=(30xx10^(-3)A)/(200xx10_(-6))=150`