Semiconducting Devices Question 4
Question: Assertion : A transistor amplifier in common emitter configuration has a low input impedence. Reason : The base to emitter region is forward biased.
[AIIMS 2004]
Options:
A) If both assertion and reason are true and the reason is the correct explanation of the assertion.
B) If both assertion and reason are true but reason is not the correct explanation of the assertion.
C) If assertion is true but reason is false.
D) If the assertion and reason both are false.
E) If assertion is false but reason is true.
Show Answer
Answer:
Correct Answer: A
Solution:
Input impedance of common emitter configuration=$\frac{\Delta V _{BE}}{\Delta i _{B}}$
where $ \Delta V _{BE}= $ voltage across base and emitter (base emitter region is forward biased) $ \Delta i _{B}= $ base current which is order of few microampere.
Thus input impedance of common emitter is low.
