Michael faraday

Michael Faraday is a great English scientist. During his lifetime he made a great number of different experiments and made valuable scientific discoveries in chemistry and physics. One of them is of great importance -the generation of electricity from magnetism.

It was well known at that time that if a piece of iron was placed inside

a coil and current was passed along the wire the iron became a magnet. Farada decided to find out whether a magnet could be made to give an electric current.

Faraday at first was quite unable to generate an electric current with mag-

nets, though he was sure that he would succeed in it He tried different positions of wires near magnets in different ways. He made coils of wire and put them round magnets. At last he decided to make the magnet near wire.

And that was the solution - he got what he wanted: an electric current pas-

sed through the wire.

That was a great moment in the history of man's electrical experi­ments. But Faraday continued his experiments. He tried other ways of pro­ducing the electric current He placed two separate coils round the iron and passed a current through one coil. He also put two coils together without the iron and passed a current through one coil. When the current was stopped, or when it was changed, another current appeared in the second coil. If there was no change in the current of the first coil, there was no current in the sec­ond one.

Then Faraday assembled an electric machine. It was rather simple in its construction: a round plate of metal between the ends of a magnet The round plate was so arranged that it could be turned round with a handle. Faraday fixed two wires which touched the turning plate. One of the wires touched the outside part of the plate and the other touched the middle. When the metal plate was turned, the machine produced electric current.

Such was the beginning of machines that make electricity today.

THE HISTORY OF COMMUNICATION

When people began to live together they saw that it was necessary to find ways for sending messages from one place to another. Even in earliest times there were several different ways by means of which people could send messages. Some used fire and smoke signals, some used couriers, men who run or ride very quickly between towns and villages.

Real communication was not possible until man discovered electricity. Scientists were carrying on experiments with electricity during the whole eighteenth century. Finally in the nineteenth century people saw the first really practical applications of electricity in the field of communications. In 1844 Samuel F.B.Morse constructed the first electric telegraph. Within a few years telegraph systems worked in many countries of the world.

About thirty years after Morse established his first telegraph system Alexander Graham Bell sent the human voice over long distances by means of electricity. His invention was the telephone.

Scientists and inventors of many countries continued to experiment with communication devices and they produced many inventions. After the telegraph and the radio, and the most recent development, is television. Mow that man is moving into the space age, quick communication over long dis­tances is becoming more important than ever.

An example of the level which communication reached in recent years is the earth satellites. As these satellites move in their orbits hundreds of miles above the surface of the earth, they collect important information about the earth and its atmosphere and send back to earth this information by means of electrical signals.

RADIO

Radio is a special kind of long-distance electrical communications. Radio was invented in Russia. The world's first receiver was built in 1895 by the great Russian scientist Alexander Popov.

Radio communication is the transfer of high-frequency energy from the transmitter to the receiver without wires. Radio is a device that transmits and receives signals and programs by electro-magnetic waves. The necessary components of radio are a transmitter and a receiver.

The transmitter is a device that produces radio-frequency energy. The main parts of it are a high-frequency oscillator including an oscillatory cir­cuit and one or more amplifiers. Radio transmission is based on the use of al­ternating currents with frequencies of hundreds, thousands and millions of cycles per second. These currents called high-frequency currents are pro­duced by means of an oscillatory circuit. This circuit consists of a coil and a capacitor.

Radio receiver demodulates waves sent out by a transmitter and they are heard as speech, music or signals.

Electric oscillations are produced in the antenna of the transmitter. They travel in all directions.

Radio waves are electric waves of very high frequency; they travel through space at the speed of light They differ from other wave forms only in frequency (number of vibrations per second).

Radio makes possible to send different signals such as dots and dashes of the Morse code (radio-telegraphy), speech and music (radio telephony), images of objects and films (television). Radio helps us to maintain contact with ships, aircraft or spacecraft. It helps us to measure distances, to make

pictures in space and so on. At present the whole of the world is covered with the wide net of powerful radio broadcast stations. Radio is a powerful means of spreading knowledge and information.

THE INVENTOR OF THE RADIO

A.S.Popov, the great Russian inventor, was born in 18S8. By the time he graduated from the Petersburg University (1883) he had already had a broad knowledge of electrical theory as well as a wide experience in that field.

Working as scientist and teacher, he carried out some practical work, solving a number of practical problems. Popov was one of the first to pay at­tention to the works of Herz, who proved by experiments the existence of electromagnetic waves. After many experiments Popov carried out together with his assistant Rybkin, the device they constructed started receiving elec­tromagnetic waves at a distance. By means of his receiver Popov could de­tect the waves at a distance of several meters and then several kilometers. While making experiments the scientist discovered that when a wire was connected to the receiver, the range of operation increased. After that he connected his first receiver to the first antenna.

On April 25, 1895, A.Popov demonstrated his device at the Russian Physico-Chemical Society. In summer 1895, Popov’s invention was success­fully tested and in the same year he attached to the device an apparatus used for recording telegrams over the wire telegraph.

In 1897, Popov successfully carried out his experiments at sea, having succeeded in effecting radio communication between the shore and the sea at a distance of 3 km.

In those days the future wireless communication between the conti­nents was being founded. The year of 1898 saw a new important invention made by Popov together with his assistants Rybkin and Troitsky - the recep­tion of signals by means of a receiver. Experiments having been completed, serious practical testing was started. In those days Popov's radio telegraph helped to save the ship "General-Admiral Apraksin".

Popov's work became known in many foreign countries.

A.S.Popov was elected director of the Petersburg Electrotechnical In­stitute. The great inventor died on the 31st of December, 1905, at the age of 47.