Page 146 - Science Class 07

this way they get virtual, erect and perform to manufacture food for themselves
enlarged image of the tooth. and for all the animals as well as human beings.

USES OF CONVEX MIRRORS We also know that, phototropic plants bend
v The rear view mirrors of the automobiles their shoot- ps towards sunlight. But photo-
are convex mirrors. A convex mirror forms tropic animals like the earthworm and the
a small erect and diminished image close cockroach turn away from light to find shelter

to the eyes of driver. into darkness.
v As a convex mirror diverges the rays of light One latest research has proved beyond doubt
over a wide area, so it is used as a street that plankton in oceans and lakes is biggest
light reflector. user of sunlight for photosynthesis, their food

LIGHT AND THE LIVING BEINGS to the extent that 45% of the oxygen of the air
is produced by plankton only.
We know very well that sunlight is essen al for
the process of photosynthesis that plants

1. What is a convex mirror?
2. Show the centre of curvature using a diagram.

3. Why convex mirrors are used as rear-view mirrors?
4. What type of image is formed when an object is placed between the pole and the focus of
a concave mirror?

5. Differen ate between real and unreal image.

Light : A form of energy
Lumen : Unit of brightness of light
Luminous : Objects which give us light

Reflection : Bouncing back of light after striking an object
Ray of light : A very narrow path of light
Beam of light : Several rays of light running parallel in a direction

Image : Illusion of an object in a reflecting surface
Convex mirror : A convex mirror has its surface curved outwardly
Concave mirror : A concave mirror has its surface curved inwardly

Let's R
Let's Revise evise evise evise evise evise evise
Let's R
Let's R
Let's R
Let's R
Let's R
I The light energy is a radiant energy that contains radio-waves, x-rays, ultraviolet rays and
infrared rays, but all these rays are not visible to the eyes.
146 Science-7