In a n-p-n transistor circuit, the collector current is 10 mA. If 80 percent of electrons emitted reach to the collector. Then the base current (in mA) will be

Answer

To find the base current (IB) in the given n-p-n transistor circuit, we can follow these steps:

### Step-by-Step Solution:

1. **Identify Given Values**:
- Collector current (IC) = 10 mA
- Percentage of electrons reaching the collector = 80%

2. **Relate Collector Current to Emitter Current**:
- Since 80% of the emitted electrons reach the collector, we can express the collector current (IC) in terms of the emitter current (IE):
\[ IC = 0.8 \times IE \]

3. **Calculate Emitter Current (IE)**:
- Rearranging the equation to find IE:
\[ IE = \frac{IC}{0.8} \]
- Substituting the value of IC:
\[ IE = \frac{10 \, \text{mA}}{0.8} = 12.5 \, \text{mA} \]

4. **Use the Relationship Between IE, IC, and IB**:
- The relationship between the emitter current (IE), collector current (IC), and base current (IB) is given by:
\[ IE = IB + IC \]

5. **Solve for Base Current (IB)**:
- Rearranging the equation to find IB:
\[ IB = IE - IC \]
- Substituting the values of IE and IC:
\[ IB = 12.5 \, \text{mA} - 10 \, \text{mA} = 2.5 \, \text{mA} \]

### Final Answer:
The base current (IB) is **2.5 mA**.

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