Sound Wave Transition: Air to Water

When a sound wave travels from one medium (like air) to another (like water), certain properties change while others remain constant. The key is understanding how the wave interacts with the properties of the new medium.

Frequency Analysis

Frequency is determined by the source of the sound wave. As the wave crosses the boundary from air to water, the source's vibration rate doesn't change. Therefore, the frequency of the sound wave:

• Remains Constant

Speed Change

The speed of sound depends on the medium's density and elasticity. Sound travels significantly faster in liquids like water compared to gases like air. This is because water is much less compressible (more elastic) and more dense than air, leading to a higher propagation speed.

• Speed Increases

Wavelength Calculation

The relationship between speed ($v$), frequency ($f$), and wavelength ($\lambda$) is given by the formula:

$v = f \lambda$

Since the frequency ($f$) remains constant and the speed ($v$) increases upon entering water, the wavelength ($\lambda$) must adjust accordingly to maintain the relationship. Rearranging the formula gives:

$\lambda = \frac{v}{f}$

As $v$ increases and $f$ stays the same, the wavelength ($\lambda$):

• Increases

Summary of Changes

When a sound wave travels from air to water:

• Frequency: Remains constant
• Speed: Increases
• Wavelength: Increases

This corresponds to option 4.