In a simple microscope of focal length `5 cm` final image is formed at `D`, then its magnification will be

Options

A. 6
B. 5
C. 2
D. 1

Explanation

To solve the problem of finding the magnification of a simple microscope with a given focal length and final image distance, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Given Values:**
- Focal length (f) = 5 cm
- Final image distance (D) = 25 cm (this is the least distance of distinct vision, often denoted as 'd')

2. **Use the Magnification Formula:**
The magnification (M) of a simple microscope is given by the formula:
\[ M = 1 + \frac{d}{f} \]
where:
- \(d\) is the least distance of distinct vision (25 cm in this case),
- \(f\) is the focal length of the lens (5 cm).

3. **Substitute the Values into the Formula:**
\[ M = 1 + \frac{25 \, \text{cm}}{5 \, \text{cm}} \]

4. **Calculate the Fraction:**
\[ \frac{25}{5} = 5 \]

5. **Complete the Calculation:**
\[ M = 1 + 5 = 6 \]

6. **Conclusion:**
The magnification of the simple microscope is 6.

### Final Answer:
The magnification is 6.

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