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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. This 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:
- 0.33 kΩ, 1.5
- 0.67 kΩ, 300
- 0.67 kΩ, 200
- 0.33 kΩ, 300
Correct answer: 0.67 kΩ, 300
Solution
The input resistance is calculated using the change in base current and the applied signal voltage, resulting in 0.67 kΩ. The voltage gain is determined by the ratio of the change in collector current to the change in base-emitter voltage, yielding a gain of 300.
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