Which process takes place in lens ?

Options

A. Reflection
B. Refraction
C. Dispersion
D. Diffraction.

Answer

### Step-by-Step Solution:

1. **Understanding the Lens**: A lens is a transparent optical element made of glass or other materials that can bend light. It has two curved surfaces.

2. **Medium Transition**: When light travels through different media, such as air (Medium 1) and glass (Medium 2), it experiences a change in speed.

3. **Refraction Process**: As light enters the lens from air into glass, it bends at the interface due to the change in speed. This bending of light is known as refraction.

4. **Path of Light**: Upon entering the lens, the light rays are refracted towards the normal (the perpendicular line to the surface at the point of incidence) if they are entering a denser medium (from air to glass).

5. **Exiting the Lens**: When light exits the lens back into air, it refracts again, bending away from the normal. This second refraction occurs at the second surface of the lens.

6. **Conclusion**: The primary process that takes place in a lens is refraction, which occurs twice: once when light enters the lens and once when it exits.

### Final Answer:
The process that takes place in a lens is **refraction**.

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