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, apiece 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.
Opaque objects : a piece of rock, a sheet of aluminium, a mirror, wooden board, a CD, ah 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. 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 objects : 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.
