Assertion:- In glass, red light travels faster than blue light.
Reason:- Red light has a wavelenght longer than blue.

Options

A. If both Assertion `&` Reason are True `&` the Reason is a correct explanation of the Assertion.
B. If both Assertion `&` Reason are True but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False.
D. If both Assertion `&` Reason are False.

Answer

To solve the given question, we need to evaluate both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "In glass, red light travels faster than blue light."
- To evaluate this, we need to consider how light travels through different media, specifically glass.

2. **Understanding the Reason**:
- The reason given is that "Red light has a wavelength longer than blue."
- This is indeed true; in the visible spectrum, red light has a longer wavelength compared to blue light.

3. **Speed of Light in a Medium**:
- The speed of light in a medium is given by the formula:
\[ v = \frac{c}{n} \]
where \( v \) is the speed of light in the medium, \( c \) is the speed of light in vacuum, and \( n \) is the refractive index of the medium.
- The refractive index \( n \) varies for different wavelengths of light due to dispersion. Generally, shorter wavelengths (like blue light) have a higher refractive index than longer wavelengths (like red light).

4. **Comparing Speeds**:
- Since blue light has a higher refractive index in glass than red light, it will travel slower than red light in that medium.
- Therefore, the assertion that "red light travels faster than blue light in glass" is indeed correct.

5. **Conclusion**:
- The assertion is true, and the reason is also true. However, the reason does not explain the assertion correctly. The speed of light in glass depends on the refractive index, which varies with wavelength, leading to the conclusion that red light travels faster than blue light in glass.

### Final Evaluation:
- **Assertion**: True
- **Reason**: True
- However, the reason does not provide a complete explanation for the assertion.

### Answer:
- The correct option is that the assertion is true, and the reason is true, but the reason is not the correct explanation of the assertion.