What Is Light?
Imagine life without light. Living in the dark... oooh! We won't be able to see the television too.Without light life is impossible. We need light to see but plants grow by absorbing light. Yet light is just one kind of "electromagnetic radiation". There are other kinds of radiations as well such as radio waves to cosmic rays. Light is the only radiation that we can see.
Where does light come from?Natural light comes mostly from the sun. The first men depended on the sun and could only see well during the day. The only way they created light was by fire.Thousands of years ago simple oil lamps were used, gas lamps were invented much later. Nowadays most lights are powered by electricity. The ordinary light bulb has a very thin wire inside called a ‘filament' which is heated when electricity passes through it and so it gives out a bright light. The bulb is filled with a specific gas which glows with a particular colour.Do you know if there wasn't light we wouldn't be able to see anything. What causes us to see is light. Let's learn more about this amazing phenomenon.
Reflection of light
Only a few objects, like the sun, are naturally luminous. We see most things by light reflecting on them, when you see a chair in daylight, what you really see is light from the sun, reflected from the chair.
What is refraction?
Have you ever noticed that a swimming pool always looks shallower than it is, or that your legs appear to bend in the middle when you stand in the bath tub! This happens because light rays bend when they pass from one transparent substance to another, in this case, from water to air. This effect is called refraction.
Colour of light
Light comes in tiny waves, some waves are short some are long. When we see colours, we see light of different wavelengths; sunlight appears to be white, but it is really a mixture of many colours. Take the example of a rainbow. We see a rainbow when there are lots of tiny droplets of water in the air and the rays of the sun are reflected from these droplets bends. Light with long wavelength i.e. red bends slightly more than light with short wavelengths, such as violet. So the colours fan out as they re-emerge from the rain drop.
Why does leaf appear to be green?
It's not the colour which it absorbs but the most reflected one! Leaf absorbs blue and red light waves and reflects green coloured rays. That's the reason why leaves appear green.
Nature of light
Two centuries ago there were two conflicting theories of light. Some scientists, following Isaac Newton believed that light is made up of tiny particles or ‘corpuscles', other such as Thomas Young thought that light consists of waves.
Today, scientists believe it is impossible to really pin down the nature of light, sometimes it acts as a wave and sometimes as particles.