Development of Electronics - I

History shows that electronics started in the pioneer days of radio communications. Television developed from radio. Furthermore, radio itself is based on earlier experiments in electricity and magnetism. The start of wireless transmission for radio communications can be taken from the work of Heinrich Hertz, a German physicist. In 1887, he was the first demonstrate the effect of electromagnetic radiation through space. The distance of transmission was only a few feet. However, the experiment demonstrated that radio waves could travel from one place to another without the need for any connecting wires between the transmitting and receiving equipment.

Hertz proved that radio waves, although invisible, travel with the same velocity as light waves. In fact, radio waves and light waves are two examples of electromagnetic radiation. This form of energy combines the effects of electricity ad magnetism. An electromagnetic wave transmits electric energy through space.

The work of Hertz followed earlier experiments on electricity and magnetism. In 1820,a Danish physicist, H. C. Oersted, showed that an electric current produces magnetic effects. Then, in 1831, a British physicist, Michael Faraday, discovered that a magnet in motion can generate electricity. The motion provides the requirement of a change in the magnetic field. In 1864, the British physicist James Clark Maxwell, on the basis of earlier work in electricity and magnetism, predicted the electromagnetic waves demonstrated later by Hertz.

The importance of this work can be judge by the fact that basic units are named after this scientists. The Maxwell (Mx) and the Oersted (Oe) are units of magnetism. The Hertz (Hz) unit is equal to one cycle per second, which is the measure for the frequency of any alternating voltage or current. The Farad (F) is the unit of capacitance, indicating how much electric charge can be stored in a capacitor.

In 1895, Guglielmo Marconi used a long wire as an antenna to develop a practical radio system for long distance. The antenna is needed for efficient radiation. He succeeded in producing wireless communication across Atlantic Ocean in 1901.