A : Young.s double slit experiment can be performed using a source of white light.
R : The wavelength of red light is less than the wavelength of other colours in white light.

Options

A. Both A and R are true and R is the correct explanation of A
B. Both A and R are true and R is not the correct explanation of A
C. A is true and R is false
D. Both A and R are false

Answer

To solve the problem, we need to analyze the two statements given:

**Assertion (A):** Young's double slit experiment can be performed using a source of white light.
**Reason (R):** The wavelength of red light is less than the wavelength of other colors in white light.

### Step-by-Step Solution:

1. **Understanding the Assertion (A):**
- Young's double slit experiment is a classic experiment in optics that demonstrates the wave nature of light through the phenomenon of interference.
- It is indeed possible to perform this experiment using white light, which consists of multiple wavelengths corresponding to different colors (red, orange, yellow, green, blue, indigo, violet).
- When white light is used, the central fringe will appear white, and the fringes on either side will display a spectrum of colors due to the different wavelengths interfering constructively and destructively.

2. **Conclusion about Assertion (A):**
- The assertion is **True** because the experiment can be performed with white light, although the resulting interference pattern will differ from that produced by monochromatic light.

3. **Understanding the Reason (R):**
- The reason states that the wavelength of red light is less than that of other colors in white light.
- However, this statement is incorrect. In the visible spectrum, red light has the longest wavelength, while violet light has the shortest wavelength.

4. **Conclusion about Reason (R):**
- The reason is **False** because it incorrectly states the relationship between the wavelengths of red light and other colors.

5. **Final Evaluation:**
- Since the assertion is true and the reason is false, we conclude that the correct answer is that the assertion is true, but the reason is false.

### Final Answer:
- Assertion (A) is True.
- Reason (R) is False.