1. Refraction of Light And
Optical Instrument
Topic:
Refraction Of Light
PHYSICS
2. Introduction
• Refraction is the bending of light ray as it
crosses from one transparent medium to
another thus causing change in direction.
Examples:
1. The bottom of swimming pool appears higher.
2. Lemons placed in a glass tumbler appear
bigger.
3. Continue
3. Letters of a book appear to be raised when
seen through a glass slab.
glass slab
4. Continue
4. A pencil partially immersed in water appears
to be twisted at the interface of water and air.
5. Refraction of Light
• When a ray of light travel from a less denser
medium to denser medium, the ray will be
reflected towards the normal and when light ray
passing from a denser medium to less denser
medium will be refracted away from the normal
this phenomena is called refraction of light
6. Example
• When the light ray
travels from air to
water, the refracted ray
bends towards the
normal.
• i – angle of incidence
r– angle of refraction
7. Continue
• When the light ray
travels from water to
air, the refracted ray
bends away from the
normal.
• i – angle of incidence
r– angle of refraction
8. Law of Refraction
The ratio of sine of angle of incidence (sin<i) to
sine of angle of refraction (sin<r) is a constant, for
all the rays of light passing through one medium
to another this constant is called refractive index
or refractive constant. It is denoted by etta (ή).
ή=
this is known as Snell’s law
9. Continue
• The refractive index or refractive constant
between two particular medium is ratio of speed
of light in first medium to speed of light in
second medium.
• ή= =
