In common - emitter configuration of a transistor, the base current `I_(E)=2muA, alpha=0.9` then the value of `I_(C)` is

Options

A. `3.0muA`
B. `2.25 muA`
C. `4.9muA`
D. `1.8muA`

Answer

To find the collector current \( I_C \) in a common-emitter configuration of a transistor, we can use the relationship between the emitter current \( I_E \), the collector current \( I_C \), and the common base current gain \( \alpha \).

### Step-by-Step Solution:

1. **Understand the Relationship**:
The relationship between the emitter current \( I_E \), collector current \( I_C \), and the common base current gain \( \alpha \) is given by:
\[ \alpha = \frac{I_C}{I_E} \]
Rearranging this gives:
\[ I_C = \alpha \times I_E \]

2. **Substitute the Given Values**:
We are given:
- \( I_E = 2 \, \mu A = 2 \times 10^{-6} \, A \)
- \( \alpha = 0.9 \)

Now, substituting these values into the equation:
\[ I_C = 0.9 \times (2 \times 10^{-6} \, A) \]

3. **Calculate \( I_C \)**:
\[ I_C = 0.9 \times 2 \times 10^{-6} = 1.8 \times 10^{-6} \, A \]
Converting this to microamperes:
\[ I_C = 1.8 \, \mu A \]

4. **Final Answer**:
Therefore, the value of \( I_C \) is:
\[ I_C = 1.8 \, \mu A \]