Chapter 11 – Light, Shadows and Reflections
1. Rearrange the boxes given below to make a sentence that helps us understand opaque objects.
Ans:
2. Classify the objects or materials given below as opaque, transparent or translucent and luminous or non-luminous:
Air, water, a piece of rock, a sheet of aluminium, a mirror, a wooden board, a sheet of polythene, a CD, smoke, a sheet of plane glass, fog, a piece of red hot iron, an umbrella, a lighted fluorescent tube, a wall, a sheet of carbon paper, the fame of a gas burner, a sheet of cardboard, a lighted torch, a sheet of cellophane, a wire mesh, kerosene stove, sun, firefly, moon.
Ans:
|
Object
|
Object is Transparent/Translucent/Opaque
|
Object is Luminous/Non-luminous
|
|
Air
|
Transparent
|
Non-luminous
|
|
Water
|
Transparent
|
Non-luminous
|
|
A piece of rock
|
Opaque
|
Non-luminous
|
|
A sheet of aluminium
|
Opaque
|
Non-luminous
|
|
A mirror
|
Opaque
|
Non-luminous
|
|
A wooden board
|
Opaque
|
Non-luminous
|
|
A sheet of polythene
|
Translucent
|
Non-luminous
|
|
A CD
|
Translucent
|
Non-luminous
|
|
Smoke
|
Translucent
|
Non-luminous
|
|
A sheet of plane glass
|
Transparent
|
Non-luminous
|
|
Fog
|
Translucent
|
Non-luminous
|
|
A piece of red hot iron
|
Opaque
|
Luminous
|
|
An umbrella
|
Opaque
|
Non-luminous
|
|
A lighted fluorescent tube
|
Opaque
|
Luminous
|
|
A wall
|
Opaque
|
Non-luminous
|
|
A sheet of carbon paper
|
Opaque
|
Non-luminous
|
|
The flame of a gas burner
|
Translucent
|
Luminous
|
|
A sheet of cardboard
|
Opaque
|
Non-luminous
|
|
A lighted torch
|
Opaque
|
Luminous
|
|
A sheet of cellophane
|
Translucent
|
Non-luminous
|
|
A wire mesh
|
Translucent
|
Non-luminous
|
|
Kerosene stove
|
Opaque
|
Luminous
|
|
Sun
|
Opaque
|
Luminous
|
|
Firefly
|
Opaque
|
Luminous
|
|
Moon
|
Opaque
|
Non-luminous
|
3. Can you think of creating a shape that would give a circular shadow if held in one way and a rectangular shadow if held in another way?
Ans: Yes, there are many things which give a circular shadow if held in one way and a rectangular shadow if held in another way. For example: a cylinder, a circular disc etc.
4. In a completely dark room, if you hold up a mirror in front of you, will you see a reflection of yourself in the mirror?
Ans: No, in a completely dark room no image will be formed because there is no light in the room so no reflection of light takes place and no image will be formed.