While travelling from air to water path of a sound beam is likely to be (see figure below):

Options

A.
B.
C.
D.

Explanation

To solve the question regarding the path of a sound beam while traveling from air to water, we can follow these steps:

### Step 1: Understand the properties of sound in different media
- Sound travels at different speeds in different media. In general, sound travels faster in denser mediums than in rarer ones.
- In this case, the speed of sound in water is greater than in air.

### Step 2: Identify the mediums
- Air is considered a rarer medium compared to water, which is denser.
- When sound travels from air (rarer medium) to water (denser medium), we need to consider how the sound beam will behave at the boundary between these two mediums.

### Step 3: Apply the principle of refraction
- According to the principle of refraction, when a sound wave passes from a rarer medium to a denser medium, it bends towards the normal line (the imaginary line perpendicular to the boundary at the point of incidence).
- Therefore, as the sound beam travels from air to water, it will bend towards the normal.

### Step 4: Analyze the options provided
- Based on the bending of the sound beam towards the normal when entering a denser medium, we can determine the correct option from the choices given.

### Conclusion
- The correct option is the one that shows the sound beam bending towards the normal as it enters the water from air.

### Final Answer
- The answer is Option 2, as the sound beam bends towards the normal when transitioning from air to water.

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