What Are Waves

Waves are disturbances that move energy from one place to another. A wave is not made of matter moving from place to place. Instead, it is energy traveling through matter.

Water waves are a good example. When you drop a stone into a pond, you see waves move outward in circles. The water itself does not travel across the pond. If you watch a leaf floating on the water, you will see it bob up and down as the wave passes. The leaf moves up and down, but it stays in about the same spot. This shows that the water moves up and down while the wave moves forward.

Waves carry energy, not matter. The energy from the stone hitting the water travels outward through the water. This is called wave motion. The water particles move up and down or back and forth, but they do not move along with the wave.

Understanding waves helps us explain many things we observe. Ocean waves carry energy from wind across great distances. Sound travels as waves through air. Light reaches Earth as waves from the Sun. All these waves have one thing in common: they move energy from one location to another without moving the material itself.