All waves of the same type in the same medium have the same speed. Which statement best describes the general dependence of wave speed?

All waves of the same type in the same medium have the same speed. Which statement best describes the general dependence of wave speed?

• A. The speed is the same for all wave types and media
• B. The speed depends only on amplitude
• C. The speed depends on the medium and the type of wave, not on frequency
• D. The speed is determined solely by the wavelength

Answer: (C)

Wave speed is set by how the medium supports that kind of disturbance. In a given medium, each type of wave has a characteristic speed determined by the medium’s properties (for example, tension and density for mechanical waves like sound, or refractive index for light). The frequency of a wave is determined by the source and, when the wave moves from one medium to another, stays the same; the wavelength changes so that v = f λ remains satisfied. Because the speed is governed by the medium and the nature of the wave rather than how fast the source vibrates, the general dependence is that speed depends on the medium and the type of wave, not on frequency. (Note: there are dispersive media where speed does depend on frequency, but that’s not the typical case described here.)

Wave speed is set by how the medium supports that kind of disturbance. In a given medium, each type of wave has a characteristic speed determined by the medium’s properties (for example, tension and density for mechanical waves like sound, or refractive index for light). The frequency of a wave is determined by the source and, when the wave moves from one medium to another, stays the same; the wavelength changes so that v = f λ remains satisfied. Because the speed is governed by the medium and the nature of the wave rather than how fast the source vibrates, the general dependence is that speed depends on the medium and the type of wave, not on frequency. (Note: there are dispersive media where speed does depend on frequency, but that’s not the typical case described here.)