Page 135 - Innovator's Science-8

Lenses

A lens is a piece of transparent material (like plastic or glass) that has one or
both the surfaces spherical. Lenses are different from mirrors as they allow
light to pass through them. We have seen a magnifying glass that is used for
reading small text. It is also used in biology laboratories for observing the
Magnifying glass
body parts of small organisms such as grasshoppers and cockroaches. A
magnifying glass is a type of lens that is used to magnify small objects.

There are two types of lenses— convex lens and concave lens
Science Convex lens is thicker in the middle than at the edges, whereas the concave
Bytes

lens is thinner in the middle than at the edges.
Testimony
The same principle used The convex lens is also known as converging lens . This is because it
in a simple magnifying converges (bends inside) the rays of light passing thought it. The concave
glass is also used in
cameras, microscopes, lens is also known as diverging lens because it diverges the rays of light
and even your eyes? A passing through it.
convex lens focuses light
rays onto a single point,
focal length focal length
forming a clear image -
just like the eye's lens
focuses light onto the
re na. When you move a axis axis axis axis
magnifying glass closer or F F
farther from an object,
you are actually adjus ng focal focal
the distance at which plane plane
light rays meet, changing Convex lens converges rays of light Concave lens diverges rays of light
how large or small the
Working of convex and concave lenses
image appears!

Aim: To show that convex lens converges the rays of
Activity-6
light whereas concave lens diverges the rays of light.
Experiential Learning
Procedure:
Take a magnifying glass (convex lens) and place it in the
path of sunlight. Adjust its posi on such that a bright
spot is formed on a piece of white paper placed on the
other side of the lens. The bright spot is the real image
of the sun. Hold the lens in this posi on for a while. We
can observe that the paper starts burning at this point.
Now repeat the ac vity using a concave lens. Real image of the
sun by convex lens
Conclusion :

We cannot get a bright spot on the paper this me. This shows that convex lens
converges the rays of light and concave lens diverges the rays of light.

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Science-8