Page 84 - SST Class 05

Mineral oil is also mined from deep below the earth’s surface. Petrol is the refined
form of mineral oil, while diesel is the residue mineral oil. Rudolf Diesel invented the
diesel engine to use this residue. Being the residue, it is cheaper than petrol. Diesel is

mainly used in large vehicles and machines, such as railway engine, ship, truck, bus,
generator etc. Diesel is also used in cars. Both petrol and diesel cause environmental
pollution.
Natural gas is also found below the earth’s surface. It is drilled using large machines. It
is now being used as a source of energy for transportation and cooking etc.

Gottlieb Daimler Rudolf Diesel A truck A generator Bombay High
Electricity
Once about 300 years ago, a toy popular among children in the Netherlands was
Leyden Jar . It was linked with two wires, one inside the glass and the other outside it.
When the two wires were joined, mild sparks and shocks were produced. The children
found it like magic.

During his visit to the Netherlands, Benjamin Franklin , an American scientist, happened
to see this toy. He found it curious. He studied it. He felt that the lightning produced
during a thunderstorm was similar to the sparks produced in a Leyden Jar. He felt that
this could be a source of energy. He decided to undertake a risky experiment.

On a cloudy day in 1752, Benjamin flew a kite and attached it with a strong silk thread.
He also attached a piece of wire to the kite and a metal key at the other end of the
thread. He noticed that whenever lightning struck, shocks were produced in the key.

He himself felt the shocks. This proved his theory that lightning has electricity. This
learning led to a number of inventions to produce electricity.
In 1800 in Italy, Alessandro Volta developed the first battery. It generated a small but
continuous flow of electricity. Other scientists went on to produce generators which

supplied a large and continuous flow of electricity. This source of energy was now
used in different fields of life.

Volta Benjamin Franklin A dam Leyden Jar

84 Contemporary Social Science-5