The power of a lens is a measure of its degree of

Options

A. convergence only
B. divergence only
C. convergence or divergence
D. none of these

Answer

To solve the question regarding the power of a lens and its relation to convergence and divergence, we can break it down into several steps:

### Step-by-Step Solution:

1. **Understanding Power of a Lens**:
- The power (P) of a lens is defined as the reciprocal of its focal length (f) in meters. The formula is given by:
\[ P = \frac{1}{f} \quad \text{(in diopters)} \]

2. **Identifying Lens Types**:
- There are two main types of lenses: concave and convex.
- A **concave lens** has a negative focal length, while a **convex lens** has a positive focal length.

3. **Analyzing the Concave Lens**:
- For a concave lens, as the focal length increases (becomes less negative), the power decreases.
- This means that the degree of divergence of light rays passing through the lens decreases.
- If the focal length is closer to zero (more negative), the rays diverge more significantly.

4. **Analyzing the Convex Lens**:
- For a convex lens, as the focal length decreases (becomes more positive), the power increases.
- This indicates that the degree of convergence of light rays increases.
- A shorter focal length means that the rays converge more quickly.

5. **Conclusion**:
- The power of a lens is a measure of its ability to converge or diverge light rays.
- In summary:
- For a concave lens, increasing the focal length decreases the divergence.
- For a convex lens, decreasing the focal length increases the convergence.

6. **Final Answer**:
- The power of a lens is a measure of its degree of convergence (for convex lenses) and divergence (for concave lenses).