Chapter 16, Problem 30A

To determine

ToDistinguish:A luminous source and an illuminated object.

Explanation of Solution

Introduction:

Objects which emit light by themselves are called luminous objects.Sun, stars, light bulbs, etc. are the best examples of luminous objects.Objects which do not reflect light are considered non-luminous objects.Sources of non-luminous objects include wood, plastics etc.

A luminous source generates its own light and heat.As an example, the Sun is a source of light i.e. a luminous object.An illuminated object on the other side absorbs light and heat from the luminous source and reflects some amount of energy.If the illuminated surface reflects the light, the surface itself appears to emit light.Moon is a perfect example of an illuminated object.

Conclusion:

Hence,the luminous sources have its own light whereas illuminated sources reflect the light of luminous sources.