If the source is moving towards right, wavefront of sound waves get modifies to

Options

A.
B.
C.
D. none of these

Explanation

To solve the problem of how the wavefront of sound waves gets modified when the source is moving towards the right, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Scenario**:
- We have a sound source that is moving towards the right.
- The sound waves are emitted in all directions from the source.

2. **Wavefront Representation**:
- A wavefront is a surface over which an oscillation has a constant phase.
- When the source is stationary, the wavefronts are evenly spaced.

3. **Effect of Source Movement**:
- As the source moves to the right, it emits new wavefronts while it is in motion.
- The wavefronts emitted after the source has moved will be closer together on the right side (the direction of movement) and farther apart on the left side.

4. **Compression and Expansion of Wavefronts**:
- On the right side (in the direction of the source's movement), the wavefronts get compressed because the source is moving towards the observer.
- On the left side (opposite to the direction of movement), the wavefronts get expanded because the source is moving away from these wavefronts.

5. **Mathematical Relation**:
- The relationship between the speed of sound (v), frequency (f), and wavelength (λ) is given by the equation:
\[ v = f \lambda \]
- When the source is moving, the effective wavelength (λ) changes based on the relative velocity of the source and the speed of sound.

6. **Conclusion**:
- Since the wavefronts on the right are compressed and on the left are expanded, we can conclude that the wavefronts are modified such that the spacing between them decreases on the right and increases on the left.

### Final Answer:
- The correct modification of the wavefronts when the source is moving towards the right is that the wavefronts on the right side get compressed, while those on the left side get expanded.