transverse wave

Meaning: In a transverse wave, the oscillation is perpendicular to the direction of energy transport. Flick a rope: the pulse runs along the rope while each piece of rope moves up and down. The medium does not travel with the wave; energy does. Wavelength is measured crest to crest. Electromagnetic waves are transverse, with electric and magnetic fields perpendicular to each other and to the direction of travel, and they need no medium. Because the oscillation has a direction, transverse waves can be polarized.

Equation: v = fλ, where v is wave speed (m/s), f is frequency (Hz), and λ is wavelength (m). For a stretched string, v = √(FT/μ), where FT is tension (N) and μ is mass per unit length (kg/m).

On the MCAT: Passages use strings with standing waves, or light with polarizers. Expect questions on how speed changes with tension, on what happens when a wave enters a new medium (f stays the same; v and λ change together), or on reading wavelength and amplitude from a displacement-versus-position graph.

Common confusion: Sound in air is longitudinal, not transverse. Its particles oscillate parallel to the direction of travel, in compressions and rarefactions, even though it is often drawn as a sine curve. Polarization is the test: transverse waves can be polarized and longitudinal waves cannot.