Light and shadows

1. SAINIK SCHOOL GOPALGANJ
CLASS –VI
SCIENCE
LIGHT ,SHADOWS AND REFLECTION
Dr A K CHOUBEY

2. LIGHT ,SHADOWS AND REFLECTION
• Light: Light is a form of energy. Light help
us to see other objects
• Luminous Objects: Objects which emit
their own light are called luminous objects
• EX: Sun, Star, Torch bulb
• Non-Luminous Objects: Objects which do
not emit their own light are called Non-
Luminous Objects.
• EX: Table , Chair

3. LIGHT ,SHADOWS AND REFLECTION
• How do we see Other objects: Light from the
sun or other source fall on other objects and
then travels Towards our eyes. (Reflected)
• Transparent objects: Objects which allow
light to pass through them are called
transparent objects
• Objects though which we can see clearly is
called transparent objects.
• E.g.: Glass. Air, Water

4. Translucent objects: Objects which allow
light to pass through them partially are
called Translucent
Objects.
Eg: oiled paper, ice, Tracing paper, Butter
paper, cloud, some kind of polythene
Opaque Objects: Objects which do not
allow light to pass through them are called
Opaque objects
Eg: Wood, Cardboard, Metal sheet

5. Shadow: Shadow is formed when an opaque object
blocks the path of light.
Properties of shadows:
1. For the formation of shadow, a source of light, an
opaque object and a screen are needed
2. Shadows are dark in color.
3. Shadows are formed opposite to the source of light
4. Shadow is always obtained on a screen / on a wall
5. Shadows can give information about the shape of
the object.( but not always)
6. Size of the shadows can be increased or decreased
if the distance between the source and object or
object and the screen are changed.

6. Rectilinear Propagation of light: LIGHT travels in
straight line. This is called Rectilinear
Propagation.
PIN HOLE CAMERA: is a toy device to study that
light travels in straight line
Properties of image formed by a Pin Hole
Camera:
1. Image formed by a pin hole camera is
coloured
2. Image formed by a pin hole camera is inverted
( upside down)
3. Image formed by a pin hole camera is smaller
in size.

7. Never look directly at the Sun: Reason:
Sunlight has UV light ( ultra violet) rays
which are harmful. Even UV light can cause
blindness
Mirror: A mirror is a polished surface which
can make the image of an object.
Types of Mirror: Plane mirror – image
formed is of the same size
Concave mirror: reflecting surface is bent –
in
Convex Mirror: reflecting surface is bulged-
out.

8. Reflection: When light falls on a mirror, it is
bounced back. Bouncing back of light is
called reflection.
Home Activity :
1) Study reflection pattern using a plane
mirror, comb and a torch
2) Make a pin hole camera
3) Collect transparent, translucent and
opaque objects with your friends.( Group Activity)

9. What is a Pinhole Camera?
A camera without a lens which uses a very small
hole pierced in one end to allow light to pass
through. An upside down image is formed on the
back of the camera which can be covered with
photography paper or film. Light rays from an
object passes through a small hole to form an
image.
The Plane Mirror -A mirror is a highly polished
surface that forms images by uniformly reflected
light.Note: images appear to be equi-distant
behind mirror and are right-left reversed.

10. Light travels in straight lines
Light travels in straight lines and this is the reason
that the opaque object obstructs the light forming a
shadow behind. We can see the light of a fixed
candle from a long pipe when the pipe is straight, but
when the pipe is bent we cannot see the light of the
candle.

11. Mirror changes the direction of light
falling on it
1.In a dark room, ask one of your friends to hold a
mirror in his/her hand at one corner of the room.
2.Stand at another corner with a torch in your hand.
3.Cover the glass of torch with your fingers and switch
it on.
4.Adjust your fingers with a small gap between them
so that you can get a beam of light.
5.Direct the beam of the torch light onto the mirror that
your friend is holding.
6.You can see a patch of light on the other side. Now
adjust the direction of the torch so that the patch of
light falls on another friend standing in the room.

12. How does light travel and get
reflected?
Fix a comb on one side of a large thermo
Col sheet
Fix a mirror on the other side.
Spread a dark colored sheet of paper
between the mirror and the comb.
Keep this in sunlight or send a beam of
light from a torch through the comb.
This activity gives us an idea of the
manner in which light travels and gets
reflected from a

13. Class 6 Videos link
https://www.youtube.com/watch?v=AbyHtfDG
8ME