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Electronics — JEE physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 ScienceJEE physicsElectronics1 Mark
Question
Assertion : A transistor amplifier in common emitter configuration has a low input impedence.
Reason : The base to emitter region is forward biased.
✓

Answer

(a) Input impedance of common emitter configuration$=\left.\frac{\Delta V_{B E}}{\Delta i_B}\right|_{V_{C E}=\text { constant }}$where $\Delta V_{B E}=$ 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.

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