Optics Notes

This is a sample of our (approximately) 5 page long Optics notes, which we sell as part of the Physics AS Level Notes collection, a A package written at Manchester High School For Girls Sixth Form in 2013 that contains (approximately) 36 pages of notes across 13 different documents.

Optics Revision

The following is a plain text extract of the PDF sample above, taken from our Physics AS Level Notes. This text version has had its formatting removed so pay attention to its contents alone rather than its presentation. The version you download will have its original formatting intact and so will be much prettier to look at.

Unit 2: 13 Optics

REFRACTION OF LIGHT

Light rays represent the direction of travel of wavefronts. Refraction is the change of direction that occurs when light passes non-normally across a boundary between two transparent substances. At a boundary between two substances, the light ray bends:

• TOWARDS the normal if it passes INTO A MORE REFRACTIVE SUBSTANCE

• AWAY from the normal if it passes INTO A LESS REFRACTIVE SUBSTANCE REFRACTION OF LIGHT BY GLASS; With glass and air;

•the light ray bends TOWARDS the normal when it passes from AIR TO GLASS

•the light ray bends AWAY from the normal when it passes from GLASS TO AIR
-the ration of sin/sinr is the same for each light ray. This is Snell's law and gives the refractive index of the material.

Refractive Index When light travelling at speed C1 in one transparent medium enters a different transparent medium in which it travels at speed C2, then refraction can occur. A measure of the amount of refraction that occurs is given by the refractive index 1N2; REFRACTIVE INDEX 1N2 = C1 C2 Refractive Index of a medium The value of 1N2 clearly depends on the nature of each medium. The refractive index of a particular medium in deﬁned as the ratio of speed of light in free space to the speed of light in the medium. REFRACTIVE INDEX OF A MEDIUM NM = C CM

Snell's Law The value of sinθ1 is a constant, for any given wavelength.

1N 2

= sinθ1 = C1 sinθ2 C2

therefore;

PHYSICS AS NOTES

sinθ2

C1sinθ2 = C2sinθ1 N1sinθ1 = N2sinθ2

32

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