Q.Describe a transverse wave.

[!TLDR] A transverse wave is one where the medium's particles vibrate perpendicular to the direction the wave itself travels, forming alternating crests and troughs. [!ANSWER] Particle vibration is perpendicular to the direction of wave propagation.

In a transverse wave, every particle of the medium in the wave's path vibrates in a direction PERPENDICULAR to the direction the wave is propagating, with the same period and amplitude as every other particle. As the wave advances, the medium divides into alternating regions of positive displacement (crests) and negative displacement (troughs); a crest together with its adjacent trough forms one complete cycle, and the wavelength is the distance between two consecutive same-phase points (crest to crest, say). Transverse waves require the medium to have elasticity of SHAPE, so they travel through solids and along liquid surfaces but not through the bulk of liquids or through gases (except electromagnetic waves, which need no medium). A transverse wave's vibration, being confined to directions perpendicular to travel, CAN be restricted to a single plane -- making it capable of being polarised. Water-surface waves are the standard everyday example. [!ANSWER] A transverse wave has particles vibrating perpendicular to the wave's direction of travel, producing alternating crests and troughs; it needs elasticity of shape and can be polarised.

State the defining relationship (perpendicular vibration vs propagation) and summarise the key characteristics from section 8.3: crests/troughs, medium requirements, and polarisability.

Giving only the bare one-line definition without any of the distinguishing characteristics (medium requirements, polarisability) that a 'describe' question is really asking for, unlike the shorter 'define' questions elsewhere in this exercise.