what does it mean for a wave to be reflected

A wave is reflected when it hits a boundary or surface and then turns around and travels back through (or along) the medium it came from instead of continuing straight on.

Simple idea

• A reflection is a change in direction of a wave at a boundary so that it returns into its original medium.

• This happens with many kinds of waves: light (in a mirror), sound (echoes), and water waves (bouncing off a wall or shoreline).

What’s happening physically?

• When a wave meets a different medium or a rigid end, part of its energy often cannot pass through, so that part is sent back as a reflected wave.

• At the boundary, the medium must satisfy certain motion/force conditions (like “no movement” at a fixed wall), and the only way to satisfy them is to create a wave going back the other way.

Direction and angles

• For waves reflecting off a smooth flat surface (like light from a mirror), the law of reflection says: angle of incidence = angle of reflection, measured from the normal (a perpendicular line to the surface).

• So “being reflected” also means the outgoing wave leaves at a specific, predictable angle that mirrors the incoming angle.

Shape and phase of the wave

• On a string with a rigid end, the reflected pulse comes back inverted (up becomes down), which is called a phase reversal of π\pi π.

• At an open or loose end, the reflected pulse comes back upright , with no phase change, even though it still travels back along the string.

Everyday examples

• Seeing yourself in a mirror is light being reflected from the glass surface back to your eyes.

• Hearing an echo in a canyon is sound reflecting off distant rock walls and returning to you after a short delay.

In short, for a wave to be reflected means it hits a boundary, cannot keep going as before, and is sent back into the original medium, often following the rule “incoming angle equals outgoing angle.”