Lesson 2 of 7

Reflection

Goal: Use the law of reflection.

Puzzles for this lesson

Word search0 of 8 foundCrossword0 of 40 letters
A still mountain lake that reflects the snowy mountains behind it like a mirror

Light bounces off a mirror. This is reflection. The angle of reflection always equals the angle of incidence.

normalincident rayreflected rayangle ofincidence, iangle ofreflection, rirmirror

Both angles are measured from the normal, not from the mirror.

  • The normal is a line drawn at 90° to the mirror, at the point where the ray hits it.
  • The law of reflection: angle of incidence = angle of reflection. A ray that arrives at 30° to the normal leaves at 30°, on the other side of the normal.
  • Your image in a flat mirror is the right way up and the same size as you. It seems to be as far behind the mirror as you are in front of it. Left and right look swapped, so writing reads backwards.

Your turn

This lesson’s activity starts here in a moment.

Check yourself

Knowledge organiser

This lesson on one page. Tap it to make it bigger.

Key words in this lesson

Ray A straight line with an arrow that shows the path of light

Reflection When light bounces off a surface

Incident ray The ray that travels towards a surface

Reflected ray The ray that leaves a surface after bouncing off it

Normal A line at 90° to a surface, from which angles are measured

Angle of incidence The angle between the incoming ray and the normal

Angle of reflection The angle between the outgoing ray and the normal

For teachers: AQA 3.4.2 · Pearson Edexcel 38.1, 38.2 · Cambridge 8Ps.01