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Reflection from a smooth, flat surface is called specular reflection.

This reflection obeys the law of reflection and is the type that happens with a flat mirror.

Properties of the image in a plane mirror

The image in a mirror is:

• upright – but left and right are reversed. The image is laterally inverted;
• the same height as the object;
• as far behind the mirror as the object is in front;
• virtual.

A virtual image is an image from which rays of light appear to diverge, and do not actually pass through.

The image appears to be behind the mirror.

A virtual image cannot be formed on a screen.

It can only be seen by looking into the mirror.

Key point

The image in a plane mirror is:

• as far behind the mirror as the object is in front;
• upright but laterally inverted;
• same size as the object;
• virtual.

Diffuse reflection

If a surface is rough, diffuse reflection happens.

Instead of forming an image, the reflected light is scattered in all directions.

This may cause a distorted image of the object, as occurs with rippling water, or no image at all.

Each individual reflection still obeys the law of reflection, but the different parts of the rough surface are at different angles.