Solved: PHYSICS Question for NEET

NEET PHYSICSMedium

In a common-emitter transistor amplifier, the audio signal voltage across the collector is $3\text{ V}$ . The resistance of the collector is $3\text{ k}\Omega$ . If the current gain is $100$ and the base resistance is $2\text{ k}\Omega$ , the voltage and power gain of the amplifier are:

100 and 1000

15 and 200

150 and 15000

20 and 2000

Step-by-Step Solution

Identify the Given Data: Collector resistance (output resistance), $R_c = 3\text{ k}\Omega$ Base resistance (input resistance), $R_b = 2\text{ k}\Omega$ Current gain, $\beta = 100$ (Note: The $3\text{ V}$ collector voltage is extra information not needed for finding the gains if $\beta$ and the resistances are known).
Calculate Voltage Gain ( $A_v$ ): The voltage gain in a common-emitter amplifier is the product of current gain and resistance gain. $A_v = \beta \times \frac{R_c}{R_b}$ $A_v = 100 \times \frac{3\text{ k}\Omega}{2\text{ k}\Omega} = 100 \times 1.5 = 150$
Calculate Power Gain ( $A_p$ ): The power gain is the product of current gain and voltage gain. $A_p = \beta \times A_v$ $A_p = 100 \times 150 = 15000$
Conclusion: The voltage gain is $150$ and the power gain is $15000$ .

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