14. Sources of Energy

The law of conservation of energy: 

Energy can niether be created nor be distroyed, It can only be transformed into one form to another form. 

Main-points: 

• The total energy during a physical or chemical process is conserved.
• Energy comes in different forms and one form can be converted to another. For example, if we drop a plate from a height, the potential energy of the plate is converted mostly to sound energy when it hits the ground.
• If we light a candle, the process is highly exothermic so that the chemical energy in the wax is converted to heat energy and light energy on burning.
• Eenergy, in the usable form, is dissipated to the surroundings in less usable forms. Hence, any source of energy we use, to do work, is consumed and cannot be used again.

Good Fuels: Fuels which would do a large amount of work per unit volume or mass, be easily accessible and be easy to store and transport are called good fuels. 

Properties of good fuels: 

(i) Which produce less pollutants. 

(ii) which would do a large amount of work per unit volume or mass.

(iii) Which are easily accessible. 

(iv) Which are easy to store and transport.

(v) Which are economicals.