SOURCES OF ENERGY
• Coal, natural gas, oil, nuclear power and other natural sources, are called primary sources of energy and electricity is the secondary energy source, that is obtained from the conversion of other sources of energy.
• Thunder and lightning are due to naturally generated electricity.
• In a lightening stroke, a very large amount of charge flows through the air, heating it up to produce the bright light. Air expands rapidly on heating producing a large sound.
Discovery of the fact that lightening is electricity by Benjamin Franklin:
• Benjamin Franklin was among the first scientists to suspect that lightning was electrical in nature. In 1752 he tested his idea by tying a metal key to a kite, and flying it in a thunderstorm.
• Sparks were produced on the wet string and key, and he felt an electric shock running through his body.
• Franklin’s investigations helped scientists figure out electric charge and led to further studies of electric current.