In a silicon transistor, a change of `7.89 mA` in the emitter current produce a change of 7.6 mA in the collector current. What change in the base current is necessary to produce an equivalent change in the collector current?

Options

A. `29 mA`
B. `0.29 mA`
C. `0.029m A`
D. Zero

Answer

To solve the problem, we need to understand the relationship between the emitter current (IE), collector current (IC), and base current (IB) in a transistor. The relationship can be summarized by the following equation:

\[ I_E = I_C + I_B \]

Where:
- \( I_E \) is the emitter current,
- \( I_C \) is the collector current,
- \( I_B \) is the base current.

Given:
- Change in emitter current, \( \Delta I_E = 7.89 \, \text{mA} \)
- Change in collector current, \( \Delta I_C = 7.6 \, \text{mA} \)

We need to find the change in base current, \( \Delta I_B \), that would produce the same change in collector current.

### Step-by-step Solution:

1. **Write the relationship for changes in currents:**
\[ \Delta I_E = \Delta I_C + \Delta I_B \]

2. **Rearrange the equation to find \( \Delta I_B \):**
\[ \Delta I_B = \Delta I_E - \Delta I_C \]

3. **Substitute the known values into the equation:**
\[ \Delta I_B = 7.89 \, \text{mA} - 7.6 \, \text{mA} \]

4. **Calculate \( \Delta I_B \):**
\[ \Delta I_B = 0.29 \, \text{mA} \]

Thus, the change in the base current necessary to produce an equivalent change in the collector current is **0.29 mA**.

### Final Answer:
The change in the base current necessary to produce an equivalent change in the collector current is **0.29 mA**.