Question

The current gain of a transistor in common emitter mode is $49$. The change in collector current and emitter current corresponding to the change in base current by $5.0 \,\mu A,$ will be

• A. $45 \,\mu A, 250 \,\mu A$
• B. $240 \,\mu A, 235 \,\mu A$
• C. $260 \,\mu A, 255 \,\mu A$
• D. None of the above

Answer 1

Answer: (A)

$45 \,\mu A, 250 \,\mu A$

Answer 2

Current gain, $\beta=\frac{\Delta I_{C}}{\Delta I_{B}}$
where $\Delta I_{C}$ is change in collector current
and $\Delta I_{B}$ is change in base current.
$\therefore \Delta I_{C}=\beta \Delta I_{B}=49 \times 5=245\, \mu A$
Also, $\Delta I_{E}=\Delta I_{B}+\Delta I_{C}$
$=(245+5) \mu A=250 \,\mu A$