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) cannot pass through it, as they would have to emerge at an angle greater than 90 degrees, which is not possible. Such rays can only be reflected back into the denser medium. The smallest angle of incidence at which total internal reflection occurs is called the critical angle.

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The law of refraction (Snell’s law) deals with the sines of the angles involved. It is most simply stated mathematically: if the angle of incidence is called I and the angle of refraction is r, then sine i/sin r is a constant, n. The constant n is known as the refractive index of the material and is a measure of how much the light is refracted on passing through the surface.

Plan:

In this investigation, in order to find out the relationship between angles of incidence and angles of refraction for a transparent material and to find the ...

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