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A transistor is operated in common emitter configuration at $V_C$ = 2 V such that a change in the base current from 100 $\mu$A to 300 $\mu$A produces a change in the collector current from 10 mA to 20 mA. The current gain is
A
25
B
50
C
75
D
100
Detailed Solution
Current gain in common emitter configuration: $\beta = \frac{\Delta I_C}{\Delta I_B}$
$\Delta I_C = 20 - 10 = 10$ mA $= 10\times10^{-3}$ A
$\Delta I_B = 300 - 100 = 200\ \mu$A $= 200\times10^{-6}$ A
$\beta = \frac{10\times10^{-3}}{200\times10^{-6}}$
$\beta = 50$
$\Delta I_C = 20 - 10 = 10$ mA $= 10\times10^{-3}$ A
$\Delta I_B = 300 - 100 = 200\ \mu$A $= 200\times10^{-6}$ A
$\beta = \frac{10\times10^{-3}}{200\times10^{-6}}$
$\beta = 50$