AQA GCSE Reflection of Waves(Physics)

Reflection of Waves

All waves can be reflected. 

Reflection is when a wave hits a boundary in a medium and bounces off the surface, without changing speed or wavelength.

Reflection of Light waves using a Mirror.

The diagram below is a very common practical that is carried out. First the equipment is set up as shown in the diagram below. 

You will need a protractor to measure the angle of incidence and angle of reflection. 

Ray box shining a beam of light at a mirror, an incident and reflected beam seen along with angle of incidence and angle of reflection to show the law of reflection

To show you clearly how to carry out the practical some of the label lines have been removed in the diagram below. 

The ray box is moved so that different angles of incidence are selected. 

moving the ray box to select different values of the angle of incidence and measuring the angle of reflection at each value.

At each angle of incidence, the angle of reflection is measured and recorded in the table below.

Angle of incidence, ioAngle of reflection, ro
1010
2020
3030
4040
5050

The pattern that you need to notice is that the angle of incidence = angle of reflection. This is known as the law of reflection!

Reflection with wavefronts and wavelengths on the diagram

The diagram with the incident and reflected ray can also be shown with the wavefronts and wavelength.

Distance between two wavefronts is one wavelength.

Notice that the wavelength is the same on both the incident and reflected wave. 

Incident and reflected ray showing wavefronts and wavelength

Practice Question

1.State what is meant by the term reflection

2. State the law of reflection

3. Write a method explaining how you can prove the law of reflection.

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