The explanation for the refraction of sound must involve
a change in
(a) frequency.
(b) wavelength.
(c) speed.
(d) all of these
The correct answer and explanation is :
The correct answer is (d) all of these.
Explanation:
Sound waves, like light waves, undergo refraction when they pass from one medium into another with different properties, such as a change in temperature, pressure, or the medium itself (e.g., air to water). Refraction is the bending of waves as they change speed due to a change in the medium. For sound, this process involves changes in speed, wavelength, and frequency, although the way these quantities change depends on the conditions.
1. Change in Speed:
The speed of sound depends on the medium through which it is traveling. For instance, sound travels faster in warmer air than in cooler air because the molecules move more quickly at higher temperatures. When sound enters a medium where its speed is different, it bends, or refracts, toward or away from the normal. The change in speed is the primary factor that causes refraction to occur.
2. Change in Wavelength:
The wavelength of a sound wave is related to its speed and frequency through the equation:
[
v = f \cdot \lambda
]
where (v) is the speed of sound, (f) is the frequency, and (\lambda) is the wavelength. Since the frequency of sound typically stays constant during refraction (assuming the source of the sound remains the same), any change in speed will directly lead to a change in the wavelength. If sound moves into a medium where it travels faster, its wavelength will increase, and if it moves into a medium where it travels slower, the wavelength will decrease.
3. Change in Frequency:
In most practical situations involving sound, frequency remains unchanged when refraction occurs. The frequency is determined by the source of the sound, and refraction typically involves a change in the medium’s properties, not the sound source. However, in certain cases (such as the Doppler effect), the frequency can change due to motion between the sound source and observer, but for typical refraction, it is constant.
Thus, refraction of sound involves changes in speed and wavelength, and while the frequency might remain constant in most situations, all three elements (speed, wavelength, and frequency) could theoretically change under different conditions.