When the base current in a transistor is changed from `30 mu A`to 80 mu A`,the collector current is changed form 1.0 mA to 3.5 mA. Find the current gain`beta`.

Explanation

Given `deltal_n = 80muA - 30 ,uA`
` = 50muA = 50xx10^(-6) A`
`delta l_c = 3.5 muA-1 mA`
`= 2.5mA = 2.5xx10^(-3)A`
`beta = ((delta l_n)/(delta l_c)) V_(cc) (Constant)`
` = (25xx10^(-3))/(50xx10^(-6)) = (250)/(50) = 50`
So, Current gain `= 50`