Reflection

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Waves can be reflected, absorbed, or transmitted at the boundary between two different materials.

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Reflection occurs when a wave hits a surface and bounces back into the original medium instead of passing through the surface. This is similar to how a ball bounces off a wall.

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Method

Draw on the 'normal'. The 'normal' is simply another word for a line that is at 90 degrees to the boundary.
Draw the incident ray. Using a protractor, measure out an angle. Using a ruler, draw a straight line along the angle to create the incident ray.
Draw on the reflected ray. Again, take your protractor and measure out the same angle as before. This time, you should be measuring the angle on the opposite side. Draw a straight line along this angle, ensuring that it touches the normal.

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You should be able to draw out ray diagrams to show the reflections of waves at a surface. To do this, you will need a sharp pencil, a ruler and a protractor.

Ray Diagrams

The 2 types of reflected waves are different. When there is specular reflection, the reflected wave will have the same angle of reflection as the angle of incidence. When there is diffuse reflection, the reflected wave will have a different angle of reflection compared to the angle of incidence.
There are 2 types of reflection. When we talk about reflection, there can be two types. They are called specular reflection and diffuse reflection. Specular reflection occurs when waves hit a smooth surface, whilst diffuse reflection occurs when the waves hit a distorted, uneven surface.

Reflection

Waves will reflect off a flat surface
The smoother the surface, the stronger the reflected wave is
Rough surfaces scatter the light in all directions, so they appear matt and not reflective
The angle of incidence = angle of reflection
Light will reflect if the object is opaque and is not absorbed by the material
- The electrons will absorb the light energy, then reemit it as a reflected wave

Transmission

Waves will pass through a transparent material
The more transparent, the more light will pass through the material
It can still refract, but the process of passing through the material and still emerging is transmission

Absorption

If the frequency of light matches the energy levels of the electrons
- The light will be absorbed by the electrons and not reemitted
- They will be absorbed and then reemitted over time as heat
- So that particular frequency has been absorbed

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If a material appears green, only green light has been reflected, and the rest of the frequencies in visible light have been absorbed

Reflection Simplified Revision Notes for GCSE Edexcel Physics Combined Science

Reflection

Ray Diagrams

Reflection

Transmission

Absorption

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