Explain why a virtual image cannot be obtained on a screen.

Explanation

### Solution:

To explain why a virtual image cannot be obtained on a screen, we need to understand the nature of virtual images and how they are formed.

1. **Definition of Virtual Image**: A virtual image is formed when light rays appear to diverge from a point. This means that the light rays do not actually converge or meet at that point in space.

2. **Formation of Virtual Image**: When an object is placed in front of a mirror or a lens, the light rays emanating from the object reflect off the mirror or refract through the lens. In the case of a virtual image, the reflected or refracted rays diverge, and if we trace these rays backward, they seem to originate from a point behind the mirror or lens.

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