In glass, the velocity of light is minimum for

Options

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

Answer

To solve the question "In glass, the velocity of light is minimum for", we will analyze the relationship between the wavelength of light and its velocity in a medium, specifically glass.

### Step-by-Step Solution:

1. **Understanding the Concept of Refractive Index**:
The refractive index (μ) of a medium is defined as the ratio of the speed of light in vacuum (C) to the speed of light in that medium (V):
\[ \mu = \frac{C}{V} \]
Rearranging this gives us:
\[ V = \frac{C}{\mu} \]
This indicates that the speed of light in a medium is inversely proportional to the refractive index.

2. **Relationship Between Wavelength and Velocity**:
The speed of light (V) in a medium can also be expressed in terms of its wavelength (λ) and frequency (ν):
\[ V = \lambda \cdot \nu \]
Since the frequency (ν) remains constant for a given light source, we can see that the speed of light in a medium is directly proportional to its wavelength.

3. **Understanding Wavelengths of Different Colors**:
In the visible spectrum, different colors of light have different wavelengths. The order from longest to shortest wavelength is:
- Red (longest wavelength)
- Orange
- Yellow
- Green
- Blue
- Indigo
- Violet (shortest wavelength)

4. **Determining Minimum Velocity in Glass**:
Since the velocity of light in a medium is inversely related to the refractive index and directly related to the wavelength, light with a longer wavelength will travel slower in glass. Among the visible spectrum, red light has the longest wavelength.

5. **Conclusion**:
Therefore, the velocity of light in glass is minimum for red light.

### Final Answer:
In glass, the velocity of light is minimum for red light.