Light, Shadows And Reflections


Q1. Rearrange the boxes given below to make a sentence that helps us understand opaque objects.


Q2. Classify the objects or materials given below as opaque, transparent or translucent, luminous or non-luminous :

Air, water, piece of rock, sheet of aluminium, mirror, wooden board, sheet of polythene, CD, smoke, sheet of plane glass, fog, piece of red hot iron, umbrella, lighted florescent tube, wall, sheet of carbon paper, flame of a gas burner, sheet of cardboard, lighted torch, sheet of cellophane, wire mesh, kerosene stove, sun, firefly, moon.


Object Object is Transparent/Translucent/Opaque Object is Luminous/Non-luminous
Air Transparent Non-luminous
Water Transparent Non-luminous
Piece of rock Opaque Non-luminous
Sheet of aluminium Opaque Non-luminous
Mirror Opaque Non-luminous
Wooden board Opaque Non-luminous
Sheet of polythene Translucent Non-luminous
CD Translucent Non-luminous
Smoke Translucent Non-luminous
Sheet of plane glass Transparent Non-luminous
Fog Translucent Non-luminous
Piece of red hot iron Opaque Luminous
Umbrella Opaque Non-luminous
Lighted fluorescent tube Opaque Luminous
Wall Opaque Non-luminous
Sheet of carbon paper Opaque Non-luminous
Flame of a gas burner Translucent Luminous
Sheet of cardboard Opaque Non-luminous
Lighted torch Opaque Luminous
Sheet of cellophane Translucent Non-luminous
Wire mesh Translucent Non-luminous
Kerosene stove Opaque Luminous
Sun Opaque Luminous
Firefly Opaque Luminous
Moon Opaque Non-luminous

Q3. 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. When a cylinder is held in sunlight, then a circular shadow or a rectangular shadow can be obtained depending on its orientation related to the Sun.

When the top of the cylinder faces the Sun, then the shadow formed is circular. On the other hand, when the side of the cylinder faces the Sun, then the shadow formed is rectangular.

Q4. In a completely dark room, if you hold up a mirror in front of you, will you see your reflection in the mirror ?

Ans. An image is formed due to reflection of light by a plane mirror. In a completely dark room, there is no light present in the room. Thus, no reflection of light takes place by the mirror placed in the room. Hence, no image will get formed by a mirror in a completely dark room.

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