A lens of focal length 20 cm is used to produce a ten times magnified image of a film slide on a screen. How far must the slide be placed from the lens?

Explanation

To solve the problem of finding the distance at which the slide must be placed from the lens to produce a ten times magnified image, we can follow these steps:

### Step 1: Understand the given values
- Focal length of the lens (f) = 20 cm
- Magnification (M) = 10 (since the image is ten times magnified)

### Step 2: Use the magnification formula
The magnification (M) produced by a lens is given by the formula:
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