The ac current gain of a transistor is 120. What is the change in the collector current in the transistor whose base current changes by `100 muA`?

Options

A. 6 mA
B. 12 mA
C. 3 mA
D. 24 mA

Explanation

To solve the problem, we will use the formula that relates the change in collector current (ΔIc) to the change in base current (ΔIb) and the current gain (β) of the transistor.

### Step-by-step Solution:

1. **Identify the given values:**
- AC current gain (β) = 120
- Change in base current (ΔIb) = 100 µA = 100 × 10^(-6) A

2. **Use the formula for current gain:**
The relationship between the change in collector current (ΔIc) and the change in base current (ΔIb) is given by:
\[ β = \frac{ΔIc}{ΔIb} \]

3. **Rearrange the formula to find ΔIc:**
To find the change in collector current, we can rearrange the formula:
\[ ΔIc = β \times ΔIb \]

4. **Substitute the known values into the equation:**
\[ ΔIc = 120 \times (100 \times 10^{-6}) \]

5. **Calculate ΔIc:**
\[ ΔIc = 120 \times 100 \times 10^{-6} = 12000 \times 10^{-6} = 1.2 \times 10^{-2} \text{ A} \]

6. **Convert to milliampere:**
Since 1 A = 1000 mA,
\[ ΔIc = 1.2 \times 10^{-2} \text{ A} = 12 \text{ mA} \]

### Final Answer:
The change in the collector current (ΔIc) is **12 mA**.

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