2. What is the difference between your
shadow and your image in a mirror ?
When we stand facing away from the
Sun, we see our shadows on the
ground in front of us.
WHAT IS SHADOW ?
HOW DOES IT FROM?
3. At the end of this unit, you will learn
about :
How light travels ?
How shadows are formed and the factors
that cause the size and shape of a shadow
to change ?
The reflection of light, ray diagram and uses
of the reflection of light in everyday life.
4. How does Light Travel ?
Look through a
You can use a torch to see rolled paper to see
things in a dark room. Look object. What you
at how the light beam from see ?
the torch.
Now, bend the paper and
look through it again. Can you see the object ?
You cannot see the object through the bend rolled
paper because light from the object cannot pass
through it. This shows that light travels in a straight
line.
5. DID YOU KNOW ???
Light travels at a speed Many events or
of 300 000 km per phenomena show
second. At this speed, that light travels in a
light from sun reaches straight line.
the Earth within 9
minutes
The search light from
The beam of light
from
lighthouse
helicopter
The ray Of
the sun
7. How Shadow does formed ?
Can you different
sizes of shadow
from the same
objects ?
Let go for get
the
Answer….
A shadow is formed when light
from a light source is blocked
by an opaque or translucent
8. Size and Shape of Shadow
The size of a shadow can be changed by
changing :
• Distance between the light source and
the object
• Distance between the object and the
screen
9. Now , you know how to change the
shape of a shadow ?
The shape and of a shadow
can be change by :
• The position of the light
source
• The position of object
10. Bouncing Light
When you look at mirror, you
see your image in the mirror .
The light from a light source
falls on you. This light is
reflected into the mirror and
the mirror reflects the image
into your eyes
11. The reflection of light can
be shown in the form of a
ray diagram.
We can see light around us because light
from a source is reflected by object
12. Reflection of
light is very
important in
everyday life
Some objects reflect light
better than others. Mirrors
and aluminium foils are good
.
reflectors of light because
their surfaces are smooth
and shiny
13. Some of the example are shown :
Periscope Dental Mirror
Side Mirror Convex Mirror
14. CONCLUSION :
1. Light travels in a straight line.
2. A shadow is formed when light is blocked by an opaque or
translucent object.
3. The size of shadow changes according to :
Distance between object and light source
Distance between screen and object
4. The shape of a shadow change according :
The position of the light source
The position of the object
5. Light can be reflected.
6. We can see an object because light from a light source that falls
onto the object is reflected by object onto our eyes.
