Solved: PHYSICS Question for NEET

NEET PHYSICSMedium

The input resistance of a silicon transistor is $100\, \Omega$ . Base current is changed by $40\, \mu\text{A}$ which results in a change in collector current by $2\text{ mA}$ . This transistor is used as a common-emitter amplifier with a load resistance of $4\text{ k}\Omega$ . The voltage gain of the amplifier is:

2000

3000

4000

1000

Step-by-Step Solution

Identify Given Data: Input resistance, $R_{in} = 100\, \Omega$ Change in base current, $\Delta I_B = 40\, \mu\text{A} = 40 \times 10^{-6}\text{ A}$ Change in collector current, $\Delta I_C = 2\text{ mA} = 2 \times 10^{-3}\text{ A}$ Load resistance, $R_L = 4\text{ k}\Omega = 4000\, \Omega$
Calculate Current Gain ( $\beta$ ):

$\beta = \frac{\Delta I_C}{\Delta I_B} = \frac{2 \times 10^{-3}}{40 \times 10^{-6}} = \frac{2000}{40} = 50$

Calculate Voltage Gain ( $A_v$ ):

$A_v = \beta \times \frac{R_L}{R_{in}} = 50 \times \frac{4000}{100} = 50 \times 40 = 2000$

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