Light is a type of energy that helps us to see all the things around us. It can be detected by the human eye and is essential for vision. When we look at a book, the light falling on the book is reflected and enters our eyes. Light is the only source of energy for plants: they produce food using energy from sunlight, carbon dioxide and water by photosynthesis.
1. Sources of Light
Objects which are able to emit light are known as light sources. There are two types: natural and artificial sources of light.
Natural Sources
- The Sun is the primary and the major source of natural light.
- Stars also produce light like the Sun, but as they are much farther away, their light is too weak.
- Some living organisms produce light by bioluminescence – the effect of certain chemical reactions in the organism. Examples: fireflies, jellyfish, glow worm, certain deep sea plants and some microorganisms.