Physics › Waves

Waves & sound

A wave is a wiggle that travels. Pluck a guitar, ripple a pond — same idea, different medium.

Wave shaper

Drag the sliders. Watch the wave breathe.

Frequency2 Hz

Amplitude40

Wavelength λ: 5.20 m

Period T: 0.50 s

v = f · λ

Three numbers describe any wave

Wavelength (λ) — distance between two crests.
Frequency (f) — how many crests pass per second. Hz.
Amplitude (A) — height of the crest. How loud / bright / strong.

Wave speed = f × λ

Sound in air travels around 343 m/s. A 200 Hz tone has a wavelength of about 1.7 m. Light travels at 300,000,000 m/s — the same equation works.

Sound: pressure waves in air

When you clap, you push molecules together. The squeeze ripples outward at the speed of sound. Your ear converts those tiny pressure changes into the bang you hear.

What changes the pitch?

Higher frequency → higher pitch.
Higher amplitude → louder.
A guitar string vibrates faster when shorter or tighter.

Reflection, refraction, diffraction

Waves bounce off walls (echo), bend when they cross materials (a straw looking broken in water), and spread around corners (you can hear someone you can't see).