Think of sunsets and traffic lights, campfires and television screens. They all give off light in many colours.
All the colours of light are given off in the same way. When atoms are heated, they soak up energy. Then they give off the energy as bundles of light.
All light comes from atoms. It is produced by atoms that have gained energy. For example, atoms take up energy when they are heated. Then they give up energy in the form of light.
This light may have a lot of energy, or just a little. The colour of the light depends on the amount of energy it has. In the visible spectrum, red light has the least energy. After red, comes orange, yellow, green, and blue. Violet light has the most energy in the visible spectrum.
In the visible spectrum, blue light has more energy than every colour except violet.
Part of the energy stored in wood is given off as light when the wood is burned.
Picture Credit : Google