Industry of Uzbekistan4

The Lucky Accident that Changed the World
It happened in Denmark in 1819. Professor Hans Oersted , while lecturing to his
students, looked down at the table where his compass was resting on wires connected to
a battery which he was using in his lectures. The professor saw that the compass had
changed its position.
The professor said, “The electric current in the wires must do something to the needle of the compass to change its position. It must affect it in some way,” Oersted said.
He said so, because the needles o the compass was a small magnet. There must be some connection between an electric current and a magnet. A few years later the electromagnet (electric magnet) was invented; all because of the professor’s important discovery.
We shall speak about the electromagnet later, but we shall just say here that
without this invention there could be no radio, no television, no motors, no large
factories, no telegraph or telephone or electric lights, no lifts, no traffic lights or signals,
not any electrical machinery of any kind.
Everything we see around us today that works on electricity has one or more
electromagnets connected with it. Without the electromagnet we should all be back in
“the horse days” of our great-great grandfathers.
And it all happened because the wires from a battery were under the professor’s compass!


Heat energy from the Sun
For many centuries, man has used the transformed heat of the Sun in the form of wood, coal,
oil or natural gas, and in a million other ways. Although, natural fuel supplies are great, some
time they will end.
Isn’t it possible to use directly the energy of the Sun?
For a long time man has been using power from the Sun directly to dry fruits and other food
products. It has also been used for heating and boiling water as well as for getting steam. Later
he began using the power for heating homes and still later for cooling things in solar
refrigerators. Nowadays, solar energy collected with the help of special reflectors has been used
in water-heaters constructed in Alma Ata.
The solar water-heater is a simple device. To make a heater one blackens the bottom and
sides of a box, coats it with heat insulating material and then covers the box with a piece of
transparent glass. Now, it is ready to be put out in the sun. Due to the sun energy, the
temperature inside the box begins to rise rapidly even if it is not a very hot day. The bottom of
the box becomes blackened; the device transforms the light of the sun into heat, while the glass
cover stops the heat from escaping. As a result, the temperature inside the box goes much more
quickly and will go much higher, if the top is covered not with one but with several sheets of
glass. The designers elaborated a water-heater with a temperature as high as 226ºC inside it - that
is, two and a quarter times the temperature of boiling water. Its box has eight sheets of glass.
Another type of a heater has been elaborated. Its box is about 16 feet long, seven feet wide
and about 7 inches high. On a sunny day, it can heat 150 gallons of water to a temperature of
about 60ºC.