2. What is Refraction
• The velocity of electromagnetic energy in a vacuum is
commonly known as the speed of light (Index of 1 - Velocity
of 300,000 km per second).
• Light travels slower in other materials such as glass (Index
of 1.5 - Velocity of 200,000 km per second).
• Light travelling from one material to another changes
speed, resulting in a change in direction of travel. This
deflection is known as refraction.
• Different wavelengths of light travel at different speeds in
an identical medium. This variation of velocity with
wavelength has an intergral role in fiber optics.
• Also of particular importance is that the index of glass can
be changed by controlling its composition.

4. • If one were to stand on a pier and look directly down
at a fish, the light would not be refracted, so the fish
would be in its apparent position, but if one were to
view that same fish at an angle, refraction of light
would occur and the fish would appear closer to the
surface. What appears to be a straight line from the
fish to the eye is actually a line with a bend where the
light passes from water into air and is thus refracted
resulting in the fish actually being deeper in the water
than it appears.

5. • The normal is an imaginary line perpendicular
to the interface of the two materials.
• The angle of incidence is the angle between
the incident ray and the normal.
• The angle of refraction is the angle between
the refracted ray and the normal.

6. Applications of Refraction
• Lens: Refraction is at the core of the functioning of a
lens. A lens uses refraction for image formation which
is used for several purposes such as magnification. Our
eye is also a lens where what we see is projected on
our retina. Here also refraction is used to form the
image on the retina. Uses of a lens in our daily life are
galore like magnifying glasses, eye glasses, contact
lenses.

7. • Prism: A prism uses refraction to form a
spectrum of colors from an incident beam
of light.A prism can be used to break light
up into its constituent spectral colours (the
colors of the rainbow). Prisms can also be
used to reflect light, or to split light into
components with different polarizations.

8. • Mirage: A mirage is a naturally occurring
optical phenomenon in which light rays are
bent to produce a displaced image of distant
objects or the sky. Some common examples
are water bodies in a desert and wet roads on
a hot sunny day.

9. Real Life examples of Refraction
• Twinkling and Shimmering: Earth’s
atmosphere consists of flowing masses of air
of varying density and temperature that
causes the refractive index to vary slightly
from one region of the atmosphere to
another. This causes refraction of light rays
coming from stars and hence the stars appear
twinkling.

11. • Ophthalmology: Refraction finds a special
place in ophthalmology where it is used as a
clinical test in which a phoropter may be used
to determine the eye's refractive error and
hence to determine the corrective measures.

12. • Other common applications are telescopes,
microscopes, etc.