Question

In the circuit shown, assuming the current gain β = 100 and V_BE = 0.7 V, what will be the collector voltage V_C in V ?
Given : V_CC = 15 V, R₁ = 100 kΩ, R₂ = 50 kΩ, R_C = 4.7 kΩ, and R_E = 3.3 kΩ

• A. 8.9
• B. 5.1
• C. 4.3
• D. 3.2

Answer 1

The Correct Option is A

To solve for the collector voltage \( V_C \) in the given transistor circuit, follow these steps:

1. First, calculate the base voltage \( V_B \) using the voltage divider rule: 
   \(V_B = \frac{R_2}{R_1 + R_2} \cdot V_{CC} = \frac{50 \, \text{kΩ}}{100 \, \text{kΩ} + 50 \, \text{kΩ}} \times 15 \, \text{V} = 5 \, \text{V}\)
2. Next, find the emitter voltage \( V_E \): 
3. Calculate the emitter current \( I_E \) using Ohm's Law: 
   \(I_E = \frac{V_E}{R_E} = \frac{4.3 \, \text{V}}{3.3 \, \text{kΩ}} = 1.3 \, \text{mA}\)
4. Assuming \( \beta = 100 \), calculate the collector current \( I_C \) (approximately equal to \( I_E \)): 
   \(I_C \approx I_E = 1.3 \, \text{mA}\)
5. Finally, calculate the collector voltage \( V_C \): 
   \(V_C = V_{CC} - I_C \cdot R_C = 15 \, \text{V} - (1.3 \, \text{mA} \times 4.7 \, \text{kΩ}) = 8.9 \, \text{V}\)

Thus, the collector voltage \( V_C \) is 8.9 V.