Give reasons for the following statements.

(a) A table does not emit any light.

(b) Light does not completely pass through a coloured bottle.

(c) A glass does not cast any shadow.

(d) The length of shadows depends on the time of the day.

(e) The size of the shadow depends on the size of the light source.

(a) A table does not emit any light because it is a non-luminous object which only reflects light falling on it, but does not produce light of its own.

(b) Light does not completely pass through a coloured bottle since a coloured bottle is translucent in nature which allows only part of the light to pass, while absorbing and scattering the rest.

(c) A glass does not cast any shadow as glass is a transparent object which allows all light to pass through, so no shadow is formed.

(d) The length of shadows depends on the time of the day because the position of the Sun changes throughout the day so in the morning and evening, light comes at a slant and forms long shadows, while at noon sunlight is overhead so short shadows are formed.

(e) The size of the shadow depends on the size of the light source because an extended source of light forms both umbra and penumbra, whereas a point source forms only a sharp umbra. A larger light source produces a larger shadow with a lighter penumbra, while a smaller light source produces a smaller, darker shadow.