S3 Physics - Ch.17 Refraction of light
17.1 Refraction of light
Light travels at different speeds in different media.
At the boundary between two media, the light ray is bent away and the phenomenon is
called refraction.
Laws of Refraction
Incident ray, refracted ray and normal are lie in same plan.
The ration of sin I to sin r is a constant, i.e. (sin i/sin r) =constant.
General form of Snell’s law
Light ray travelling from medium 1 to medium 2. The general form of Snell’s law is
Calculate method of the slope of graph:
When comparing two media, the one with a larger refractive index is called the optically
denser medium and the other is called the optically less dense medium.
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17.2 Phenomena due to refraction of light
Real depth = it is the actual depth which the body or container has
Apparent depth = it is the depth which is visible or which is seen by us after the refraction, etc
When an observer under water views
some objects above the water surface, the image of the
object appears
farther to the observer than it actually is.
Refraction in prism and dispersion
17.3
Total internal reflection
When a light ray enters an optically less dense medium, it bends away from normal. As the angle
of incidence increases, the angle of refraction also increase until it reaches 90°. In this case, the
refracted ray travels along the boundary between two media.
Critical angle and refractive index
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17.4 Examples of total internal reflection
Fish-eye view :
Mirage
Total internal reflection in prism
Application of prisms
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Total internal reflection in a diamond
Prisms are used to reflect light because it can avoid the formation of multiple images, and the
image formed is clearer.
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