In a common base transistor circuit, the current gain is 0.98. On changing the emitter current by 1 mA, the change in collector current is

Options

A. `0.196mA`
B. `2.45mA`
C. `4.9 mA`
D. `0.98 mA`

Answer

To solve the problem, we need to understand the relationship between the emitter current (IE), collector current (IC), and the current gain (α) in a common base transistor configuration.

### Step-by-Step Solution:

1. **Understanding the Current Gain (α)**:
The current gain in a common base transistor is defined as the ratio of the change in collector current (ΔIC) to the change in emitter current (ΔIE). Mathematically, this is expressed as:
\[ \alpha = \frac{\Delta I_C}{\Delta I_E} \]

2. **Given Values**:
From the problem, we have:
- Current gain (α) = 0.98
- Change in emitter current (ΔIE) = 1 mA = \(1 \times 10^{-3}\) A

3. **Calculating Change in Collector Current (ΔIC)**:
Rearranging the formula for current gain, we can express the change in collector current as:
\[ \Delta I_C = \alpha \cdot \Delta I_E \]
Substituting the known values:
\[ \Delta I_C = 0.98 \cdot (1 \times 10^{-3}) \text{ A} \]

4. **Performing the Calculation**:
\[ \Delta I_C = 0.98 \times 1 \times 10^{-3} = 0.98 \times 10^{-3} \text{ A} = 0.98 \text{ mA} \]

5. **Conclusion**:
The change in collector current (ΔIC) when the emitter current changes by 1 mA is:
\[ \Delta I_C = 0.98 \text{ mA} \]

### Final Answer:
The change in collector current is **0.98 mA**.

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