For a transistor `1/alpha -1/beta` is equal to

Options

A. two
B. three
C. one
D. zero

Explanation

To solve the problem, we need to find the expression for \( \frac{1}{\alpha} - \frac{1}{\beta} \) in terms of the transistor parameters \( \alpha \) and \( \beta \).

### Step-by-step Solution:

1. **Understand the relationship between \( \alpha \) and \( \beta \)**:
The relationship between the common base current gain \( \alpha \) and the common emitter current gain \( \beta \) is given by:
\[ \beta = \frac{\alpha}{1 - \alpha} \]

2. **Express \( \frac{1}{\beta} \)**:
From the relationship, we can express \( \frac{1}{\beta} \):
\[ \frac{1}{\beta} = \frac{1 - \alpha}{\alpha} \]

3. **Substitute \( \frac{1}{\beta} \) into the expression**:
Now, we substitute \( \frac{1}{\beta} \) into the expression \( \frac{1}{\alpha} - \frac{1}{\beta} \):
\[ \frac{1}{\alpha} - \frac{1}{\beta} = \frac{1}{\alpha} - \frac{1 - \alpha}{\alpha} \]

4. **Simplify the expression**:
Now, we can simplify the expression:
\[ \frac{1}{\alpha} - \frac{1 - \alpha}{\alpha} = \frac{1}{\alpha} - \frac{1}{\alpha} + \frac{\alpha}{\alpha} = \frac{\alpha}{\alpha} = 1 \]

5. **Conclusion**:
Therefore, we find that:
\[ \frac{1}{\alpha} - \frac{1}{\beta} = 1 \]

### Final Answer:
The expression \( \frac{1}{\alpha} - \frac{1}{\beta} \) is equal to **1**.