A lens is called a thin lens if its overall thickness is

Options

A. small
B. large
C. infinitely large
D. none of these

Answer

To determine when a lens is classified as a thin lens, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Lens Thickness**: A lens is a transparent optical device that refracts light. The thickness of the lens plays a crucial role in its classification.

2. **Definition of Thin Lens**: A lens is referred to as a "thin lens" when its overall thickness is relatively small compared to its other dimensions (like its radius of curvature).

3. **Comparison of Thickness**:
- If the thickness of the lens (denoted as 't') is very small, it can be approximated that light rays passing through the lens will not be significantly affected by the thickness.
- Conversely, if the thickness is large, the lens would not be classified as thin since the effects of the thickness would alter the path of the light rays more noticeably.

4. **Conclusion**: Therefore, a lens is called a thin lens if its thickness is small.

5. **Final Statement**: In summary, the correct condition for a lens to be classified as a thin lens is that its thickness must be very small.