What is Electricity?

            In ancient times, man took the flash of lightning during a thunderstorm as a signal of impending destruction from the heavens or the displeasure of god. With passage of time, science progressed and the mystery of this great energy called electricity unfolded.

Layout of Thermal Power Station

            As early as 600 B.C. Greeks discovered electricity by rubbing amber with cloth, which enabled it to attract small pieces of papers. In fact, the word electric originated from the Greek word electron. Based on the theory of electromagnetic induction of Michael Faraday in 1831, first successful generator or dynamo was made in Germany in 1867. U.S.A. produced electricity by running turbines with the help of falling water in 1858.

            Today, we cannot imagine the normal life without electricity. We know it as a form of energy that powers almost all machines or mechanical devices- trains, radios, television sets, freezers and so on.

            Electricity is a phenomenon involving electrical charge and its effects, either at rest or in motion. Electricity that we use flows through wires as electric current. Electric current, which flows through a conductor of a given resistance, produces heat. Particles of a matter may be positive, negative or neutral. We know that electricity has its two important particles- protons and electrons. Electron is negatively charged while a proto is positively charged. An element containing an equal number of protons and electrons is electrically neutral. For example, anode is a positive electrode while cathode is a negative one.

            Electricity that we use is produce in power stations. In the generator of a power station, coils of wire are made to rotate between powerful magnets, which induce electric current into the coils. The electricity produced is further distributed through metallic wires. Materials through which electricity can travel are called conductors, i.e. substances like copper, aluminum and iron. Materials through which electricity cannot pass are called insulators, i.e. materials like rubber, wood and glass.

            After the invention of the electric cell by Alessandria Volta, man realized that light heat, chemical reactions and magnetic effects could be produced from electricity.

            Electricity, which flows in one direction and then in the opposite is called alternate current (A.C.). Each movement of A.C. back and forth happens very quickly-about 50 times in a second. The electricity that we use at houses is normally A.C. steady flow of current in one direction is known as direct current (D.C.) for example, battery current is D.C.

            Today, hydroelectric and thermal power stations are the most popular methods of producing electricity. During the 20^th century, many nuclear power stations were constructed to meet the growing demand of electricity.

What is Electromagnetism?

            In 1820, Hans Christian’s Oersted of the University of Copenhagen observed that a compass gets deflected when placed near a wire, and electricity is passed through it. It also returns to its normal position when the current is switched off. It made Oersted realize that electric current produced magnetic effects. The relationship between magnetism and electricity was established in later years and the study of electricity and magnetism came to be known as electromagnetism.

An Electromagnet

            Subsequently, Michael faraday carried out further studies in the field of electromagnetism. The current passing through a wire produced a magnetic field, and this magnetic property was harnessed to produce motion in electric motors. But faraday went a step further- if a current can create a magnetic field, then ca a magnet produce electric current, he asked himself.

            Faraday discovered that it was not the magnetic field that created the current in a wire, but the movement of magnetic lines of force across the wire that produced the current. When a magnet, either an electromagnet or a permanent magnet, is moved ear an electrical conductor, turbulent current are induced in the conductor, which move around it. The conductor experiences a dragging force and electricity is induced in it. This force is regulated to produce an electric current like in a dynamo.

            A more complex example of electromagnetism is found in transformers where a changing magnetic field produces current. Here tow coils of wire are placed close to each other and an alternating current is passed through one coil, a changing magnetic field is produced which induces an alternating current I the second coil.

            Electromagnets are used in telephone ad electric bells. In scrap yards, powerful electromagnetic devices are used to separate iron and steel scraps from accumulated junk in steel and iron plants.

Can Matter be converted into Energy?

            In 1995 Albert Einstein established a relationship between mass and energy which is known as the mass-energy relation formula. According to this formula if a mass m is converted into energy, then e=mc2 where E is the energy released and C is the velocity of light. According to this formula the energy available by the conversion of half a pound of matter will be equal to that produced by exploding 7 million tones of dynamite.

Atom Bomb converts Matter into Energy

            Scientists realized the real importance of the mass energy relationship in 1945, when the first atom bomb converting uranium into energy was exploded by U.S.A. on 6 august 1945, the uranium atom bomb was dropped on Hiroshima in Japanese. There days later a plutonium atom bomb killed millions of Nagasaki. These bombs killed millions of people. Scientists realized the true potential of unclear energy. Subsequently on the basis of this formula, more powerful hydrogen bombs were developed.

             After seeing the great destruction in Hiroshima and Nagasaki scientists thought of tapping this energy for peaceful purposes. Nuclear power plants have been developed to generate electricity on the basis of this formula. Heat energy produced in reactors by the fission of uranium is used for converting water into steam to run turbines which in turn run generators. These generators produce millions of megawatts of electric power. Einstein mass energy relationship and its subsequent practical applications have proved to be a great boon to mankind. About 1% energy needs of the world are now met by nuclear energy.