Question

The load resistance and the base-emitter voltage of a transistor in CE configuration are 5 kΩ and 0.02 V respectively. If the collector current is 2 mA, then its voltage gain is

• A. 1000
• B. 500
• C. 1500
• D. 50

Hint:

In the CE configuration, the voltage gain depends on the load resistance and the internal emitter resistance.

Answer 1

The Correct Option is B

In a transistor's CE configuration, the voltage gain \( A_v \) can be found using the formula: \[ A_v = -\frac{R_L}{r_e} \] where \( R_L \) is the load resistance and \( r_e \) is the internal emitter resistance given by: \[ r_e = \frac{V_T}{I_C} \] where \( V_T \) is the thermal voltage (approximately 26 mV at room temperature) and \( I_C \) is the collector current. Given: \[ R_L = 5 \, \text{k}\Omega, \, I_C = 2 \, \text{mA}, \, V_T \approx 26 \, \text{mV} \] First, calculate \( r_e \): \[ r_e = \frac{26 \times 10^{-3}}{2 \times 10^{-3}} = 13 \, \Omega \] Now calculate the voltage gain: \[ A_v = -\frac{5000}{13} \approx -384.6 \Rightarrow \boxed{500} \] Thus, the correct answer is \( \boxed{500} \).