Critical angle of light passing from glass to air is least for

Options

A. red
B. green
C. yellow
D. violet

Explanation

To solve the question regarding the critical angle of light passing from glass to air, we will follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Critical Angle**:
The critical angle is the angle of incidence above which total internal reflection occurs when light travels from a denser medium to a less dense medium. It can be calculated using the formula:
\[ \theta_c = \sin^{-1}\left(\frac{1}{\mu}\right) \]
where \(\mu\) is the refractive index of the medium from which light is coming.

2. **Identify the Refractive Index**:
The refractive index varies for different colors of light. Generally, the refractive index is highest for violet light and lowest for red light in the visible spectrum. This is due to the dispersion of light.

3. **Relate Refractive Index to Critical Angle**:
Since the critical angle is inversely related to the refractive index, a higher refractive index will result in a smaller critical angle. Therefore, if the refractive index for violet light is maximum, the critical angle will be minimum.

4. **Conclusion**:
Given that the question asks for the critical angle of light passing from glass to air being least, and knowing that violet light has the highest refractive index, we conclude that the critical angle is least for violet light.

5. **Final Answer**:
Thus, the critical angle of light passing from glass to air is least for violet light.