An object 4.0 cm in size, is placed 25.0 cm in front of a concave mirror of focal length 15.0 cm.
At what distance from the mirror should a screen be placed in order to obtain a sharp image?

Explanation

To find the distance from the mirror where a screen should be placed to obtain a sharp image of an object in front of a concave mirror, we can use the mirror formula:

### Step-by-Step Solution:

1. **Identify Given Values**:
- Size of the object (H₀) = 4.0 cm (not needed for distance calculation)
- Object distance (u) = -25.0 cm (negative as per sign convention for concave mirrors)
- Focal length (f) = -15.0 cm (negative for concave mirrors)
...