Learning goals

•     To illustrate the reflection of light.
  
  

Summary

Reflection of light from a plane mirror.

Click and drag the mirror around the screen.
Click and drag the red handle to tilt it.

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The light rays reflected off a plane mirror obey Snell-Descartes’ laws, which state that the angle of reflection of a light ray is equal to its angle of incidence.

A plane mirror displays stigmatism,  meaning that each point of the object corresponds to a single point of the image, which makes them perfectly symmetric with respect to the plane of the mirror. For the reflection to be perfect, the defects on the reflecting surface must be smaller than the wave length of the light (a few hundredths of a micrometer).
To amplify light, lasers use two flat mirrors set face to face, one being non-reflecting to allow the ray to be emitted outside the device.
Telescopes use large concave mirrors which focus all the light on the eyepiece or on a test instrument.