Does radio actually carry sound? Yes, radio uses radio waves to carry sound from one place to another. In radio broadcasting, plays, music or other sounds are turned into electromagnetic waves in a microphone.
These are transmitted by an aerial, or a tall mast. They are picked up by another aerial on a receiver. The radio sets in homes are receivers; they change the signal back into sound.
The radio was invented by Guglielmo Marconi, in 1895. The first radios sent messages in morse code. Today, messages are sent all over the world by radio, which is called radiotelegraphy. Soldiers, police, doctors and other groups can keep in touch with each other by radio.
The first radio programmes for entertainment were broadcast from radio stations in the 1920s. Now most countries have a number of radio stations.
What Does a Radio Uses to Carry Sound? How Is a Radio Wave Emitted?
OK. So we have a signal that is sent to a radiosmitter’s antenna. How does that signal get from the antenna to the air?
Let’s first take a look at the signal. The signal is an electic current, and every electric current is actually electrons moving in a wire.
Wire is made of metal, usually copper. All of the atoms that make up the wire have something in common — each has one or two electrons in its outer-most shell.
These electrons do not have a strong bond with the rest of the atom. In fact, it takes just a slight amount of energy to push the electron away from its atom.
But if you have enough energy, the outer electrons from all of the atoms will move at once. They will each travel from one atom to the next atom, and so on.
Back to our radio signal. The electrons in our wire are moving, but not in one direction. These electrons are moving back and forth.
Actually, the wave displayed in the activity is a representation of the back and forth movement of electrons. If the wave has a frequency of 200,000 Hz (cycles per second), the electrons in the wire are moving back and forth 200,000 times a second.
When electrons move in a wire, an electromagnetic field is created around that wire. There’s no magic behind this; it’s just the way things work.
Just as the electrons move in the wire, they move in the transmitter’s antenna. And just as an electromagnetic field is created around the wire, a field is created around the antenna.
But there is a difference between the wire and the antenna. The wire is shielded (surrounded by another wire) to keep the electromagnetic field in. The antenna, on the other hand, is designed to radiate the electromagnetic field.
The electromagnetic field travels from the antenna in all directions and at the speed of light. It travels until it hits your radio’s antenna as well as hundreds of other receiving antennas.
And what happens at the receiving antenna? Just as a current in a wire produces an electromagnetic field, an electromagnetic field produces current in a wire (or antenna). This current is then amplified and processed by the radio.
Content for this question contributed by Shannon Fry, resident of Aptos, Santa Cruz County, California, USA
