The various forms of energy mentioned get converted from one form to another in different situations. This phenomenon of converting one form of energy to another form is called energy transformation.
Potential energy of water stored in a dam changes into kinetic energy as water falls from a height. The kinetic energy of flowing water changes into kinetic energy of rotation of a turbine. The coil attached with the shaft of the turbine rotates in a magnetic field to convert kinetic energy of rotation of the turbine into electrical energy.
An electric bulb (or tube light) converts electrical energy into light energy, electric oven (or heater or iron or soldering iron) convert electrical energy into heat energy and electric pump (or motor) converts electrical energy into mechanical energy.
An electric cell converts chemical energy into electrical energy; solar cell converts light energy into electrical energy and a thermocouple changes heat energy into electric energy.
A microphone converts sound energy into electrical energy and a loudspeaker changes electrical energy into sound energy.
Heat engine converts heat energy into work (mechanical energy) and work done against friction is converted into heat.
During transformation of energy from one form to another it remains constant. This is known as Law of Conservation of Energy.