Know that for a transverse wave, the direction of vibration is at right angles to the direction of propagation and understand that electromagnetic radiation, water waves and seismic S-waves (secondary) can be modeled as transverse

3.1 General Properties of Waves

Transverse Waves 🌊

A transverse wave is one where the displacement of the medium is perpendicular to the direction the wave travels. Imagine a rope being shaken up and down while the wave moves to the right. The up‑down motion is the vibration, and the rightward motion is the propagation.

  • ⚡ Light waves: the electric and magnetic fields oscillate perpendicular to the direction of travel.

  • 🌊 Water waves: the water particles move up and down while the wave moves forward.

  • 🛠️ Seismic S‑waves: the ground shakes sideways while the wave moves through the Earth.

Mathematically, if the wave travels in the +x direction, the displacement is along the y‑axis, giving a 90° angle between the two directions.

Wave equation for a transverse wave:

\$y(x,t) = A \sin(kx - \omega t)\$

Wave TypeDirection of VibrationPropagation DirectionExample
TransversePerpendicular (⊥)Along the waveLight, water, S‑waves
LongitudinalParallel (∥)Along the waveSound, P‑waves

Quick Check 🎯

  1. Which wave type has vibration perpendicular to propagation? Answer: Transverse.

  2. Give an example of a transverse wave that is not light. Answer: Water wave or seismic S‑wave.

  3. What is the angle between vibration and propagation in a transverse wave? 90°.

Remember, the key idea is the 90° relationship between how the medium moves and the direction the wave travels. This property lets us model many natural phenomena as transverse waves.