A convex lens of focal length 10 cm and imag formed by it, is at least distance of distinct vision then the magnifying power is

Options

A. 3.5
B. 2.5
C. 1.5
D. 1.4

Answer

To solve the problem, we need to find the magnifying power of a convex lens when the image is formed at the least distance of distinct vision. Here are the steps to arrive at the solution:

### Step-by-Step Solution:

1. **Identify the Given Values:**
- Focal length of the convex lens, \( F = 10 \) cm.
- Least distance of distinct vision, \( D = 25 \) cm.

2. **Understand the Formula for Magnification:**
- The magnifying power (magnification) \( M \) of a lens when the image is formed at the least distance of distinct vision is given by the formula:
\[ M = 1 + \frac{D}{F} \]
where \( D \) is the least distance of distinct vision and \( F \) is the focal length of the lens.

3. **Substitute the Values into the Formula:**
- Now substitute \( D = 25 \) cm and \( F = 10 \) cm into the magnification formula:
\[ M = 1 + \frac{25}{10} \]

4. **Calculate the Value:**
- Simplifying the equation:
\[ M = 1 + 2.5 = 3.5 \]

5. **Conclusion:**
- Therefore, the magnifying power of the lens is \( M = 3.5 \).

### Final Answer:
The magnifying power is \( 3.5 \).

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