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The aims of this investigation are to find the relationship between the angles of incidence and the angles of refraction for a transparent material and to find the critical angle of the transparent material.

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Physics GCSE Coursework- Refraction of light

The aims of this investigation are to find the relationship between the angles of incidence and the angles of refraction for a transparent material and to find the critical angle of the transparent material.

Refraction is the bending of light rays that occurs when they pass from one transparent material, or medium, to another. When light passes from a less dense medium (for example, air) to a denser one (for example, glass) it is refracted towards the normal (an imaginary line perpendicular to the surface). This occurs because the light waves are slowed down by the denser medium, causing them to change direction. On leaving the glass block, exactly the opposite occurs: the light is refracted away from the normal on passing back to the less dense medium.

One everyday effect of refraction is that objects seen under water appear to be at a shallower depth than they really are. The observer sees an underwater object in a higher position, because the eye cannot tell that the light has been refracted on its path from the object.

Due to light travelling from a denser to a less medium is refracted away from the normal, some rays striking the surface at a larger angle of incidence (angle between the ray and the normal)

...read more.


A block of PerspexA rayboxA protractorTwo wiresPlain piece of A4 paperPlug socketPencilBattery pack

Whilst conducting the experiment, the safety precautions, which I am going to take, are: I will place all the equipment in the middle of the table, so that any equipment does not fall and cause any nasty injuries to anyone. I will also make sure that I don’t switch on any electricity on until I had all the wires connected and was ready, so that there would be no risk of anyone having an electric shock.


  1. Collect all the equipment and place it in the middle of the desk.
  2. Connect wires to the battery pack and the raybox.
  3. Connect battery plug to the plug socket and switch the plug on.
  4. Place block of Perspex on plain piece of paper and draw around it.
  5. Move the raybox five to eight degrees each time using a protractor and draw in results with a pencil.

Once I had all my results I drew a table with my results filled in:

Angle of Incidence

Angle of Refraction













After I completed my table, I noticed that as my angle of incidence became greater so did my angle of refraction but this was by a greater margin than the angle of incidence.

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After completing this investigation I have realised that the relationship between the angles of incidence and the angles of refraction is that as the angles of incidence become greater so do the angles of refraction but the angles of refraction increase in a larger amount and the first table which I drew shows this. I also think that the critical angle for a glass block is around 54 degrees, it may not be exactly 54 degrees but I know that it is around 54 degrees.

In this investigation, I have learnt a lot about refraction, which I did not know before. I have learnt that refraction is always caused by the waves changing speed and that when waves slow down they bend towards the normal.

I think that most of my results are pretty accurate, except for one of the results, which is a bit of track and my line graph, shows this. I think that I carried out the experiment well. I think that if I were to carry out this investigation again then I would probably make sure that my results were more accurate by either making sure that I am moving the raybox the same distance each time or by carrying out the experiment twice and comparing the results. If I were to carry out the investigation again then I would complete the experiment much quicker and so I would save a lot of useful time.

...read more.

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