The magnification power of a convex lens of focal length 10cm, when the image is formed at the near point is

Options

A. 6
B. 5.5
C. 4
D. 3.5

Explanation

To solve the problem of finding the magnification power of a convex lens with a focal length of 10 cm when the image is formed at the near point, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Near Point**:
- The near point is the closest distance at which the eye can focus on an object clearly. For a normal human eye, this distance is typically taken as 25 cm.

2. **Identify Given Values**:
- Focal length of the convex lens (F) = 10 cm
- Distance of the near point (D) = 25 cm

3. **Use the Magnification Formula**:
- The formula for magnification (m) when the image is formed at the near point is given by:
\[ m = 1 + \frac{D}{F} \]

4. **Substitute the Values into the Formula**:
- Substitute D = 25 cm and F = 10 cm into the magnification formula:
\[ m = 1 + \frac{25}{10} \]

5. **Calculate the Magnification**:
- Simplify the fraction:
\[ m = 1 + 2.5 = 3.5 \]

6. **Conclusion**:
- The magnification power of the convex lens when the image is formed at the near point is 3.5.

### Final Answer:
The magnification power is **3.5**.

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