Specular reflection is reflection from a smooth surface in a single direction.
Diffuse reflection is reflection from a rough surface in multiple directions.
The angle of incidence equals the angle of reflection. Angles are measured from the normal.
Light can be thought of as a wave (ripples) in electric and magnetic fields.
Like all waves, light can be represented using rays or wavefronts.

Common misconception

Pupils often think that light rays are actual physical things that are the constituents of light.

It needs to be made explicit through teaching that light rays are imaginary lines that show the direction in which light is travelling.

Keywords

Specular reflection - Specular reflection is reflection from smooth surfaces in one direction.
Diffuse reflection - Diffuse reflection is reflection from rough surfaces in multiple directions.
Ray - A ray is a straight line drawn to represent the direction that a light wave travels.
Normal - The normal is an imaginary line drawn at 90° to a surface.
Wavefront - Wavefronts are lines drawn to represent peaks of a wave.

Specular and diffuse reflection can be demonstrated engagingly using a torch or laserpen aimed at flat kitchen foil (for specular reflection) and then crumpled kitchen foil. 'Pepper's ghost' is a well-known and engaging illusion that demonstrates the partial transmission and reflection of light.

Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.

Match each angle to its description.

Correct Answer:90°,this is the angle between one side of a square and the next side

this is the angle between one side of a square and the next side

Correct Answer:180°,if you turn by this angle, you face in the opposite direction

if you turn by this angle, you face in the opposite direction

Correct Answer:360°,if you turn by this angle, you face in the same direction as before

if you turn by this angle, you face in the same direction as before

Q2.

The protractor is measuring the angle between the two lines. What is the correct measurement?

Correct answer: 35°

45°

145°

155°

Q3.

Which letter is labelling a peak (also called a crest) of this wave?

Correct answer: b

Q4.

A person holds a lit candle in front of a mirror and is looking at the candle’s reflection. Starting with where the light is given out, put these objects into the order of the path the light takes.

1 - the candle

2 - the mirror

3 - the person's eyes

Q5.

What happens to light when it reflects off an object?

the light enters the object but does not come back out

the light passes through the object

Correct answer: the light bounces off the surface of the object

Correct answer: the light changes direction

the light continues travelling in the same direction

Q6.

Which letter represents one wavelength?