23 January 2020

Relation between current amplification factor α and current amplification factor γ



                      α = ∆IC / ∆IE……….. ( 1 )
  • It is defined as the ratio of the output current ( emitter current ) and input current (  base current ).
  • It is ratio of the change in emitter current to the change in base current.

                      γ = ∆IE / ∆IB………….( 2 )
Relation between α and γ
As IE = IC + IB
∆IE = ∆IC + ∆IB
Therefore ∆IB = ∆IE – ∆IC………. ( 3 )
From equation ( 2 ) and ( 3 )
γ = ∆IE / ∆IE – ∆IC
Divide numerator and denominator by ∆IE
γ = [ ∆IE / ∆IE ]  / [ ∆IE – ∆IC ] / ∆IE
   = 1 / ( 1 – α )
 γ = 1 / ( 1 – α ) 
       OR
γ ( 1 – α ) = 1
γ – γα = 1
γ – 1 = γα
α = ( γ – 1 ) / γ
 α = ( γ – 1 ) / γ

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