Energy is the ability of a physical system to perform work. We use energy in our daily lives from various sources for doing work. We use muscular energy for carrying out physical work, electrical energy for running multiple appliances, chemical energy for cooking food etc.

The unit of measurement in the International System of Units (SI) of energy is the joule, which is the energy transferred to an object by the work of moving it a distance of one metre against a force of one newton.

Common forms of energy include the kinetic energy of a moving object, the potential energy stored by an object’s position in a force field (gravitational, electric or magnetic), the elastic energy stored by stretching solid objects, the chemical energy released when a fuel burns, the radiant energy carried by light, and the thermal energy due to an object’s temperature.

We need to know various energy sources to obtain the energy in its usable form. Here you will be familiarized with two important sources of energy: conventional energy and non-conventional energy.