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An NPN transistor is used in common emitter configuration as an amplifier with 1 kΩ load resistance. Signal voltage of 10 mV is applied across the base-emitter. The produces a 3 mA change in the collector current and 15 μA change in the base current of the amplifier. The input resistance and voltage gain are
- 0.67 kΩ, 300
- 0.67 kΩ, 200
- 0.33 kΩ, 1.5
- 0.33 kΩ, 300
Correct answer: 0.67 kΩ, 300
Solution
The input resistance is calculated using the change in base-emitter voltage and base current, yielding 0.67 kΩ. The voltage gain is determined by the ratio of the change in collector current to the change in base-emitter voltage, resulting in a gain of 300.
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