Class 6 - Physics - Light Shadow and Reflection

Question1.

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

Physics Light Table 1

Answer:

 Physics Light Table 2

Question2:-

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 flame of a gas burner, a sheet of cardboard, a lighted torch, a sheet of cellophane, a wire mesh, kerosene stove, sun, firefly, moon.

Answer:

Opaque materials are those objects which does not allow light to pass through them. Example: - Wooden board, umbrella.

Transparent materials are those objects which allow light to pass through them in straight lines. As a result we can see the objects clearly. Example: - Plane mirror, water.

Translucent materials are those which let some light to pass through them, the light rays get scatter in all directions, so cannot see clearly through them. Example: - Fog, smoke.

Luminous objects are those which emit light on their own. Example:-Sun, firefly.

Non-luminous objects are those which reflect the light from luminous bodies. Example: - Moon, mirror.

Based on the above definitions we can classify the objects as opaque, transparent, translucent, luminous and non-luminous.

Opaque:  A piece of rock, a sheet of aluminium, a mirror, a wooden board, a CD, an umbrella, a wall, a sheet of carbon paper,  a sheet of cardboard.

Transparent: Air, water, a sheet of plane glass.

Translucent: A sheet of polythene, smoke, fog, a sheet of cellophane, a wire mesh.

Luminous: A piece of red hot iron, a lighted fluorescent tube, the flame of a gas burner, a lighted torch, sun, firefly, kerosene stove.

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, an umbrella, a wall, a sheet of carbon paper, a sheet of cardboard, a sheet of cellophane, a wire mesh, kerosene stove, moon.

Question 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?

Answer :

The shadow obtained from a cylinder can be either rectangular or circular it depends upon which face of the cylinder is facing the sunlight.

Physics Light Shadow

Question 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?

Answer:

 No we will not be able to see our reflection in the mirror in a completely dark room.

Image is formed by a mirror due to the reflection of light from any object.

But in case of a completely dark room there is no light so no reflection as a result no image is formed.

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