waves and energy

Question

I cannot for the life of me properly understand waves and energy in physics, no matter how many definitions and explanations I come across.

I can do calculations with all of these things, but I have trouble understanding what they represent in reality. Can I touch a wave? Is a wave a physical thing like an object, that moves up and down? Ditto for energy.

The definitions of these things are kinda unhelpful. Defining wave as “thing that transfers energy” doesn’t tell me what that *thing* is, for example; it just tells me something about the thing.

In: 6

Answer 1

> Is a wave a physical thing like an object, that moves up and down?

Leaving aside electromagnetic waves for a moment:

A wave is not a physical thing, it is a certain kind of movement of physical things.

Let’s star with something easy to visualize: Line up a bunch of hockey pucks, each about an inch apart, and then hit the first one so that it collides with the second one. The first puck pretty much stops and the second puck moves until it collides with the third puck. The second puck stops while th third puck starts moving. The energy gets transferred from the beginning of the line of pucks to the end of the line of pucks even though there is very little movement of the pucks themselves.

This is an approximation of a wave. The pucks are the *medium* that carries the wave energy.

A medium most people are familiar with is water. The water molecules move a bit and return to their original location while the wave energy moves across the water.

> Can I touch a wave?

Sure. Haven’t you ever felt a water wave hit you? You feel the water of course -it’s wet and cold – but the force of the water hitting you is the wave.

Sound waves have air as a medium. You hear things because your ears are sensitive enough to feel the waves.

The tricky waves are electromagnetic waves because they don’t have a physical medium the way other waves do. Instead they have two wave forces that feed off each other. The electric wave creates a magnetic wave. The magnetic wave creates an electric wave. The electric wave creates a magnetic wave…