Gravitation

Gravitation is a very important force in the universe. Every object has a gravitational pull which is like magnet­ism. But, unlike magnetism, gravitation is not only in iron and steel. It is in every object large or small; but large objects, such as earth, have a stronger pull than small ones.

Isaac Newton, the great scientist of the seventeenth century, first studied gravitation. When he was a boy, he often saw how apples fell to the ground. He wondered why they fell towards the earth and why they did not fly up into the sky.

According to ^lthe law which he later produced every­thing in the universe attracts everything else towards it­self. The sun attracts the earth and the earth attracts the sun. The earth attracts the moon and the moon attracts the sun. Although the bigger object has the stronger attraction, all objects, in fact,²have some attraction too but we do not notice the gravitational pull of a book be­cause the pull of the earth is very much greater.

Why does the earth always move round the sun, and not fly off into cold space? The sun's gravitation gives the answer. The earth always tries to move away in a straight line, but the sun always pulls it back. So it con­tinues on its journey round and round the sun.

The sun is one of the stars in the galaxy, in which there are about 100,000 million stars. It is not in the middle of the galaxy, but rather ³near one edge.

There are millions of galaxies in the universe and so there are thousands of millions of millions of suns. Many astronomers believe that some of these suns have planets as our sun does.

Gravitation is the force which holds all the atoms of a star together. It holds the sun together and it holds the atoms of the earth together. It holds us on the earth.

Einstein produced a new law of gravitation. Its main results are the same as the results of Newton's law; but in very small and fine matters Einstein's law gives differ­ent results. One of these is that gravitation bends light a little; but according to Newton's law gravitation has very little effect on light. Einstein showed this fact by means of mathematics and not by experiment. And astron­omers later proved by experiments that Einstein was right.

Notes

1. according to—в соответствии с

2. in fact — на самом деле, фактически

3. but rather — аскорее

Uses of electricity

Electricity is the power that has made possible the engineering progress of today. Wherever we look around us, we can find this power serving us in some way.

When we use a switch and have our room instantly flooded with light, we seldom think of what is happening to make it possible. Probably the most important use of electricity in the modern home is producing light.

Do you know that the first ever man-made electric light illuminated the laboratory of the St. Petersburg physicist Vasily Petrov in 1802? He had discovered the electric arc, a form of the gas discharge. But in Petrov's experiments the arc flame lasted for only a short time.

In 1876 Pavet Yablochkov invented an arc that burned like a candle for a long time and it was called "Yabloch-kov's candle". The source of light invented by Yablochkov won world-wide recognition. But while he and several other inventors were improving the arc light, some engi­neers were working along entirely different lines. They sought to develop an incandescent lamp.¹It was a young Russian engineer, Alexander Lodygin, who made the first successful incandescent lamp. The famous American in­ventor Thomas Edison improved the lamp having used a carbon filament. But it was again Lodygin who made anoth­er important improvement in the incandescent lamp, having invented a lamp with a tungsten filament, the lamp we use today.

Another electric light we use today is the light of the luminescent lamp—a "cold" daylight lamp.²Artificial daylight lamps are much cheaper than incandescent lamps and last much longer. This is the lighting of the future.

The uses of electricity in the home do not end with lighting. There are more and more electric devices helping us in our home work.

But we should not forget that electricity is the most important source of energy in industry as well. A worker in- a modern manufacturing plant uses on the average in the machines which he operates over 10,000 kilowatt-hours of electrical energy a year. This means that he uses enough electrical energy to supply seven or eight modern homes during a year.

Automation which is one of the main factors of techni­cal progress today is impossible without electricity.

Our life can't be imagined without telephone, telegraph and radio communications. But it is also electricity that gives them life. In recent years electricity has made a great contribution to radio communication between the space­ships and also between the astronauts and the earth.

Little could be done in modern research laboratory without the aid of electricity. Nearly all of the measuring devices used in developing nuclear power for the use of mankind are electrically operated.

Notes

1. incandescent lamp '— лампанакаливания

2. "cold" daylight lamp — «холодная» лампа дневного света