Question

In a CE transistor amplifier, the signal voltage across the collector resistance is 2.5 V. The input signal voltage is 0.02 V. If the base and collector resistances are 1.5 k\(\Omega\) and 2.5 k\(\Omega\), find the current amplification factor.

• A. 100
• B. 50
• C. 75
• D. 125

Hint:

In CE amplifier, \(\beta = \frac{V_C R_B}{V_B R_C}\). Always consider collector and base resistor ratios along with voltage signals.

Answer 1

The Correct Option is C

Step 1: Compute the base and collector currents separately.
\[ I_B = \frac{V_B}{R_B} = \frac{0.02}{1500} = 1.333\times10^{-5}\ \text{A} \]
\[ I_C = \frac{V_C}{R_C} = \frac{2.5}{2500} = 1\times10^{-3}\ \text{A} \]
Step 2: Take the ratio to get the current amplification factor.
\[ \beta = \frac{I_C}{I_B} = \frac{1\times10^{-3}}{1.333\times10^{-5}} \]
Step 3: Divide.
\[ \beta \approx 75 \]
\[ \boxed{75} \]