Draw a neat labelled ray diagram showing the formation of an image at the least distance of distinct vision D by a simple microscope. When the final image is at D, derive an expression for its magnifying power at D.

Explanation

### Step-by-Step Solution

**Step 1: Draw the Ray Diagram**
1. Draw a simple microscope consisting of a convex lens.
2. Mark the principal axis and label the lens as 'L'.
3. Place an object 'AB' at a distance 'U' from the lens.
4. Draw two rays from the top of the object 'A':
- One ray parallel to the principal axis which refracts through the lens and passes through the focal point on the opposite side.
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