Ray optics is valid, when characteristic dimensions are

Options

A. of the same order as the wavelength of light
B. much smaller than wavelength of light
C. of thr order of one millimeter
D. much large than the waveiength of light

Answer

To solve the question regarding when ray optics is valid, we need to consider the relationship between the characteristic dimensions of the objects involved and the wavelength of light. Here’s a step-by-step solution:

### Step-by-Step Solution:

1. **Understanding Ray Optics**:
- Ray optics, also known as geometrical optics, is a branch of optics that describes light propagation in terms of rays. It is applicable when the size of the objects and apertures involved is much larger than the wavelength of light.

2. **Characteristic Dimensions**:
- Characteristic dimensions refer to the size of the objects or apertures that light interacts with. This could include the diameter of a lens, the size of an aperture, or the dimensions of an obstacle.

3. **Wavelength of Light**:
- The wavelength of visible light is typically in the range of 400 nm (violet) to 700 nm (red). For ray optics to be applicable, the characteristic dimensions must be significantly larger than this range.

4. **Condition for Ray Optics**:
- The key condition for ray optics to be valid is that the characteristic dimensions should be much larger than the wavelength of light. This can be mathematically expressed as:
\[ \text{Characteristic Dimension} \gg \text{Wavelength of Light} \]
- If the characteristic dimensions are comparable to or smaller than the wavelength, phenomena such as diffraction occur, which are better explained by wave optics.

5. **Conclusion**:
- Therefore, ray optics is valid when the characteristic dimensions are much larger than the wavelength of light.

### Final Answer:
Ray optics is valid when characteristic dimensions are much larger than the wavelength of light.

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