6.2 : Refraction
Words to learn
Converge >> to meet or come together
Convex lens >> a bulging shape lens
focal point >> the point where rays of light converge
Lens >> a transparent material such as glass or plastic with at least one
curved surface
Medium >> a material such as air, water or glass
optical illusion >> something our eyes see but it is not real
Refract / refraction >> the bending of light
(i) Refraction is the bending of light.
(ii) Refraction occurs because light travels at different
speeds through different mediums.
(iii) A medium is a material such as water, glass or air.
E.g. The ray of light from the pencil bends or refracts as it
goes from the water to the air.
This is called an optical
illusion.
An optical illusion is
something our eyes
see but which is not
real or in this case, not
in real position
An optical illusion is something our eyes see but which is not real.
Look at the real position of the fish.
The ray of light from the fish bends or refracts as it goes from the
water to the air.
real position of the fish
Sofia thinks the fish
is in a direct line
from her eyes.
This is called an
optical illusion.
Why is refraction important
Due to the refraction of light through glass,
(a) we can see the objects from very far positions through eyeglasses,
sunglasses , binoculars and for space, telescopes.
(b) we can see the small objects using magnifying glass , even super
small objects using microscope.
(c) In fact , even our eyes view objects through lens by the refraction of
light from the object and the image appears inverted on the retina
which is corrected by brain.
A lens is a transparent substance with at
least one curved surface.
Lenses refract light in useful ways.
Our eyes have lenses in them!
Other lenses that we use may be made of
glass or transparent plastic.
(i) The lens bends light rays as they pass through
it, so the rays change direction.
(ii) This means the rays seem to come from a
point that is closer or further away than they
actually do.
(iii) This is what makes objects seen through a
lens appear either bigger or smaller than they
really are.
A convex lens makes things look bigger.
Things such as spectacles, magnifier,
microscope, binoculars and telescopes use
convex lenses.
In convex lens, the light rays pass through the
lens and bend inward and meet or converge at a
point just beyond the lens.
The light rays pass through the lens and
bend inward and meet or
converge at a point just beyond the lens.
This point where the rays converge is called
the focal point.
Convex lenses are used to make eyeglasses,
projectors, microscopes, binoculars and
telescopes.
The lens brings distant light rays to a focus in
our eyes.
Some telescopes have such strong convex
lenses that we can see distant planets and
moons in the solar system.
How a telescope works
How a telescope works