A : Doppler's effect in sound is asymmetric but in light , it is symmetric
R : In Sound , change in frequency depends on the individual velocity of both the source as well as the observer . In light , change in frequency depends on the relative velocity between source and observer .

Answer

To analyze the given assertion and reason regarding the Doppler effect in sound and light, let's break it down step by step.

### Step 1: Understanding the Assertion
The assertion states that "Doppler's effect in sound is asymmetric but in light, it is symmetric."

- **Asymmetric in Sound**: This means that the change in frequency observed when either the source or the observer is moving is not the same. The formula for the Doppler effect in sound is given by:
\[ f' = \frac{v + v_o}{v - v_s} \cdot f \]
where:
- \( f' \) = apparent frequency
- \( v \) = speed of sound in the medium
- \( v_o \) = speed of the observer (positive if moving towards the source)
- \( v_s \) = speed of the source (positive if moving away from the observer)

### Step 2: Analyzing the Asymmetry
When the observer moves towards the source, the frequency increases, and when the source moves towards the observer, the frequency also increases, but the changes are not equal. Thus, the effect is asymmetric.

### Step 3: Understanding the Reason
The reason states that "In sound, change in frequency depends on the individual velocity of both the source as well as the observer. In light, change in frequency depends on the relative velocity between source and observer."

- **Individual Velocities in Sound**: For sound, both the velocities of the source and observer affect the observed frequency distinctly, leading to the asymmetry.

- **Relative Velocity in Light**: In the case of light, the frequency change is dependent only on the relative velocity between the source and observer, making it symmetric. This means that the frequency change will be the same regardless of whether the source or observer is moving.

### Step 4: Conclusion
Both the assertion and reason are true. However, the reason does not adequately explain the assertion. Therefore, while both statements are correct, the reason is not the correct explanation for the assertion.

### Final Answer
- **Assertion (A)**: True
- **Reason (R)**: True, but does not explain A.