Page 27 - cbse-class-10-light-reflection-and-refraction

The perpendicular drawn to the surface of separation at the point of incidence is
called the normal.

Refracted Ray (OR)

The ray of light which travels into the second medium, when the incident ray
strikes the surface of separation between the media 1 and 2, is called the refracted
ray.

Angle of Incidence (i)

The angle which the incident ray makes with the normal at the point of incidence,
is called angle of incidence.

Angle of Refraction (r)

The angle which the refracted ray makes with the normal at the point of incidence,
is called angle of refraction. A ray of light refracts or deviates from its original
path as it passes from one optical medium to another because the speed of light
changes.

Laws of Refraction

The incident ray, the refracted ray and the normal to the surface at the point of
incidence all lie in one plane. For any two given pair of media, the ratio of the sine
of the angle of incidence to the sine of the angle of refraction is a constant. The
above law is called Snell's law after the scientist Willebrod Snellius who first
formulated it

Thus,

sini  a constant  
sin r

Where µ is the refractive index of the second medium with respect to the first
medium.

The refractive index of glass with respect to air is given by the relation.

In general, if a ray of light is passing from medium 1 to medium 2, then

If the medium 1 is air or vacuum, the refractive index of medium 2 is referred to as
the absolute refractive index. The refractive index of a medium depends on the

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