NEET2005PhysicsSemiconductorsActual
Assertion : In a common emitter transistor amplifier the input current is much less than the output current. Reason : The common emitter transistor amplifier has very high input impedance.
Options
- AIf both assertion and reason are true and reason is the correct explanation of assertion
- BIf both assertion and reason are true but reason is not the correct explanation of assertion
- CIf assertion is true but reason is false
- DIf both assertion and reason are false.
Correct answer
C. If assertion is true but reason is false
Step-by-step solution
A good amplifier stage is one which has high input resistance and low output resistance. A transistor in C B configuration has a very low input resistance ( 20 ) and a very high output resistance ( 1 M ). It is just the reverse of what is required. The C E configuration is better, its input resistance is about 1 k and output resistance about 10 k . Although input resistance of C E is not very high but it still prefers better amplifier.