SSC PHYSICS

Introduction
       

Did you know that the famous American inventor Benjamin Franklin almost killed himself in his famous kite experiment? 
He was actually trying to establish that sometimes clouds (like during a thunderstorm) had an electric charge and he wanted to bring the charge down to earth through the string of the kite! 
He did succeed in showing that electricity flowed through the string, which was noticed by the sparks between the key attached to the string.
         

Perhaps this was the first experiment that established that current flowed from a higher charge level (like the charged clouds) to earth. Again, the sparks were not noticed initially, when the silken thread flying the kite was dry. When it rained, electricity flowed, as the wet string became a conductor due to the moisture. A good conductor was therefore necessary for the flow of the electric current.
     

Electricity has existed in the world since the beginning of time. Man has been aware of it for over 2000 years, but it is only recently that he has understood what electricity is and how it works. Benjamin Franklin was the first to prove, in 1752, that the electricity of the atmosphere is identical in nature to the electricity obtained artificially in the laboratory. His experiment with the kite and key confirmed that electricity existed in nature!
             

An Italian physicist, named Allesandro Volta, invented the first device to produce continuous electricity. Other scientists like Galvani and Michael Faraday can be credited with the study and behaviour of electricity. Thus was born a new stream in Physics, that is, electric current.
          

Electric current is the movement of electrons in a conductor that produces electricity. Hence all transmission lines and other wiring are made of metal, which is a good conductor.

When electricity was established as a real source of energy, it had to be transmitted to the consuming centres. Conversion of this energy into useful work is made possible through numerous electrical machines. 

One cannot see electricity but observe its effects in the form of sparks or when something lights up, or feel it when a shock registers in your system. In modern times, we can see its effect in the form of lighting in our houses, electrical appliances, entertainment gadgets, communication, transport, etc. It is the cleanest form of energy for distribution. It causes no pollution at the consuming centres at all. Attempts are on  to make electrical cars instead of the polluting gasoline cars.        
Much of modern technology is driven by current electricity.