Law of Reflection
Light, Sound and Waves

Your very own mirror invention!

Classroom Activity for 11-14 Supporting Physics Teaching

What the Activity is for

This activity provides the opportunity for pupils to apply their knowledge of the law of reflection of light from a plane mirror in an imaginative way.

What to Prepare

  • devise a starter support sheet that will get your class off on the right lines, if necessary

What Happens During this Activity

Tell the class that they are going to use their knowledge of the law of reflection of light to invent a device, based on flat mirrors, which no-one else has thought of before. Encourage the class to let their imaginations fly. The device might, for example, be:

  • Used to look at boils on the back of your neck.
  • Attached to the end of your shoe so that you can see under tables.
  • Used to see over high walls around football grounds.
  • Set up so that you can watch the TV in the living room from the stairs, without being detected by your parents.


Think up an unusual invention that works using flat mirrors. Don't make it too complicated!

Make a careful drawing of your invention, showing each of the mirrors clearly. Draw in a single ray to show how it passes around the mirrors and to your eye.

At each of the mirrors be sure to include the normal line and mark the angles of incidence and reflection.

Although the device itself may not be altogether serious, you should insist that the diagrams are accurately drawn to demonstrate the law of reflection of light.

Law of Reflection
is expressed by the relation θ_i=θ_r
formalises Reflection
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