Paragraph on “What are Radio Waves?” complete paragraph for Class 9, Class 10, Class 11 and Class 12

What are Radio Waves?

Radio waves are like light except that we cannot see them with our eyes and they are harder to stop. They can go through walls, for example. In fact, light and radio waves are both examples of ‘electromagnetic radiation’. Like light, radio waves travel 300,000 km (I 86,000 miles) each second and go in straight lines unless blocked (by something like thick concrete) or reflected.

Because the earth is round we cannot send radio signals straight to someone a long way away. Instead we bounce them off a layer high in the atmosphere, called the ‘ionosphere’, which reflect radio waves. Sometimes we use special satellites to receive them and re-transmit them down to earth. The picture below shows how this happens.

As so many people want to send radio messages each transmitter sends out only one ‘wavelength’ of radio waves. The different wavelengths are like different shades of colour in ordinary light. We ‘tune’ the receiver to pick up only one wavelength — the signals from the transmitter we want.