Answer
Opaque Objects Make Shadow
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 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 objects : 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 objects : Air, Water, a sheet of polythene, a sheet of plane glass, a sheet of cellophane, a wire mesh
Translucent objects : smoke, fog
Luminous objects : A piece of red hot iron, a lighted fluorescent bulb, the flame of a gas burner, a lighted torch, kerosene torch, sun, firefly
Non-luminous object : 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, moon.
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
A cylindrical shape can give a circular shadow when light is incident from its top or bottom. It will give a rectangular shadow when light is incident from its side.
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 because there is no source of light in the room.