Physics
Wave Behavior
Quick fact
When waves meet, they can pass through each other without permanently changing direction—a phenomenon called superposition.
Why this is interesting
You've seen waves at the beach, but did you know that sound and light behave in similar ways? How can a whisper travel around a corner?
Read the full explanation
Understanding Wave Behavior
Imagine dropping a pebble into a still pond: ripples spread outward. If a barrier blocks part of the wave, the ripple bends around the edge—that's diffraction. When the wave hits a wall, it bounces back—reflection. If it enters shallower water, it slows and bends—refraction. When two ripples cross, the water height at any point is the sum of the individual disturbances—superposition. These same principles apply to sound waves bending around a doorway or light waves creating rainbow patterns in a soap bubble. The key idea is that waves transfer energy without moving matter, and their interactions follow predictable, additive rules.
A deeper explanation
All wave behavior stems from the principle of superposition: the net displacement at a point equals the sum of the displacements from each wave. This leads to interference—constructive (peaks align) or destructive (peaks cancel troughs). Reflection occurs because a wave's path is altered at a boundary; the nature of the boundary (fixed or free) determines if the wave is inverted. Refraction is caused by a change in wave speed due to a different medium, altering direction via Snell's law. Diffraction describes how waves spread when passing through openings or around obstacles; the effect is strongest when the obstacle size is comparable to the wavelength. These interactions are not just academic—they explain how lenses focus light, how ocean waves shape coastlines, and how noise-cancelling headphones use destructive interference to silence sound.