Which statement describes a transverse wave?

• A. The medium travels parallel with the direction of travel.
• B. The amplitude is crest to rest
• C. The particle motion is perpendicular to the direction of travel
• D. The frequency is independent of wavelength

Answer: (C)

In a transverse wave, the oscillations of the medium are perpendicular to the direction the wave travels. Picture a string being plucked: the string moves up and down while the wave moves along the string's length. That up-and-down motion relative to the horizontal travel is what defines a transverse wave, producing crests and troughs.

The statement that best captures this is that the particle motion is perpendicular to the direction of travel. The other ideas describe different aspects or other types of waves: motion parallel to the travel direction describes longitudinal waves (like sound in air); amplitude being the distance from rest to crest is a general property of waves and isn’t unique to transverse waves; and frequency and wavelength are tied by the wave speed (f times λ equals the speed), so they aren’t independent in a simple, uniform medium.