Question

The transistor Q1 has a current gain \( \beta_1 = 99 \) and the transistor Q2 has a current gain \( \beta_2 = 49 \). The current \( I_{B2} \) in microampere is \(\underline{\hspace{2cm}}\). 

Hint:

When calculating the current for a transistor using the current gain, remember to apply the formula for each transistor separately, based on the given current gains.

Answer 1

Correct Answer: 10

Using the current gain formula, the current gain for a transistor is related to the base current and the collector current by:
\[ I_{C1} = \beta_1 I_{B1} \text{and} I_{C2} = \beta_2 I_{B2} \] The total collector current is given as \( I_{C1} + I_{C2} = 50 \, \text{mA} \).
Since the collector current for Q2 is \( I_{C2} = \beta_2 I_{B2} \), and the relationship between \( I_{B1} \) and \( I_{B2} \) can be calculated, we find that: \[ I_{B2} = \frac{I_{C2}}{\beta_2} = \frac{50 \, \text{mA}}{49} \approx 1.02 \, \mu\text{A}. \] Thus, the value of \( I_{B2} \) is approximately \( 1.02 \, \mu\text{A} \).