JEE Main & Advanced
JEE Main Paper (Held on 08-4-2019 Afternoon)
question_answer
A common emitter amplifier circuit, built using an npn transistor, is shown in the figure. Its dc current gain is \[250,{{R}_{C}}=1k\Omega \]and \[{{V}_{CC}}=10V.\] What is the minimum base current for \[{{V}_{CE}}\] to reach saturation? [JEE Main 8-4-2019 Afternoon]
A)\[100\mu A\]
B)\[7\mu A\]
C)\[40\mu A\]
D) \[10\mu A\]
Correct Answer:
C
Solution :
At saturation state, \[{{V}_{CE}}\]becomes zero \[\Rightarrow \]\[{{i}_{C}}=\frac{10V}{1000\Omega }=10mA\] now current gain factor \[\beta =\frac{{{i}_{C}}}{{{i}_{B}}}\] \[\Rightarrow \]\[{{i}_{B}}=\frac{10mA}{250}=40\mu A\]