AQA GCSE Reflection, Transmission and absorption of Waves at a Surface(Physics)

Reflection of Waves at a surface

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.

Smooth, Shiny Surfaces

Smooth, shiny surfaces such as a mirror are always good reflectors. This will give a regular reflection. 

Regular reflection from a smooth surface or specular reflection

Rough Surfaces.

Although the light will reflect, it will not be a regular reflection, instead it will be a scattering of the light. This is know as diffuse reflection.

Diffuse reflection, scattering of light rays from a rough surface

Transmission and Absorption

When a wave strikes the surface of the material, it may or may not pass through the material.

Transmission and absorption of a wave through a material, showing the amplitude decreasing due to the material absorbing energy of the wave

As the wave passes through the material, some of the energy of the wave is absorbed by the material. So, the amplitude of the wave decreases. This is why the transmitted wave has a lower amplitude than the incident wave. 

The energy of the wave, is transferred to the thermal energy store of the material, so the temperature of the material will increase slightly.

The more energy absorbed by the material, the greater the increase in temperature of the material and the bigger the decrease of the amplitude of the wave.

Practice Question

1.Define the term reflection

2. Explain the difference between regular reflection and scattering. 

3. Aluminium foil is squashed into a ball and then unfolded to make a bumpy surface. If a beam of light is shone onto the foil, what would happen?

4. Explain why the amplitude of a wave decreases as it passes through a material.

Accordion Content

Accordion Content