When sound waves travel from one medium to another, such as from air to water or vice versa, their behavior can be described by the principles of wave propagation and the phenomenon of refraction. The wavelength of the sound waves can change when crossing the interface between two mediums.
At the interface between two media, such as air and water, the speed of sound typically differs due to the difference in density and other properties of the two substances. In general, sound waves travel faster in water than in air. When a sound vibrator produces sound waves in the water, and those waves reach the water-air interface, several things can happen:
Reflection: Part of the sound wave can bounce back from the interface, reflecting off the surface of the water. This reflection can cause echoes or reverberation.
Transmission: Another part of the sound wave can continue to travel into the air. However, as the sound waves transition from water to air, their speed decreases, while their frequency remains the same. This change in speed affects the wavelength.
According to the relationship between wavelength, frequency, and speed of sound (wavelength = speed of sound / frequency), if the speed of sound decreases (as it does when transitioning from water to air), and the frequency remains constant, the wavelength must decrease as well. In other words, the wavelength of the sound waves would generally become shorter at the water-air interface.
This change in wavelength can impact the way the sound is perceived. For example, if the sound vibrator produces a continuous tone, the sound waves might have a longer wavelength in the water and a shorter wavelength in the air, resulting in a change in pitch when transitioning between the two mediums.
It's important to note that the exact behavior of sound waves at an interface depends on various factors, including the angle of incidence, the properties of the materials involved, and any potential obstacles or structures present. The discussion above provides a general understanding of the wavelength changes at an interface between water and air, but specific scenarios may yield more complex outcomes.