Plane wave

A plane wave is like a very long and straight string that can vibrate up and down to make a sound. Imagine holding a ruler and shaking it up and down really fast. The vibration from the ruler would be like a plane wave.

When we talk about plane waves in science, we mean they are similar to the waves made by a vibrating string but they move through the air or other materials, like light, sound or microwaves. These waves travel in a straight line and have a constant shape, like a line of waves at the beach.

Picture a kid on a bike riding down a flat road in a straight line. The bike and the road are like the waves, moving forward in a straight line without any curves or bumps. A plane wave is similar to this, moving straight and uniform through space.

Now imagine those same waves at the beach being created by a machine that always made the same size waves in the same pattern, and it created waves that never lost any energy. This would be like a plane wave because it would always look the same and move in a straight line, without ever getting weaker or spreading out.

So, a plane wave is really just a specific type of wave that is uniform, moves in a straight line, and never loses energy.