An electrical conductor moves across a magnetic filed and electric current is induced. There is a powerful filed magnet, between the poles of which the armature is rotated. This mechanical energy is converter into electrical energy in the form of a current in the armature. Water is said to be hard when it does not readily form lather with soap. Hardness is due mainly to the presence of sulphates, chlorides and nitrates of calcium and magnesium in water.
Water is said to be soft, if it readily forms latter with soap.
Distilled water and rainwater are examples of soft water. To avoid the process of combustion, the air inside the electric bulb is removed by evacuation or alternatively the bulb is filled with an inert gas like argon or helium. Waterfalls flowing on turbines, which are power units working on the principle of the water wheel, convert kinetic energy into mechanical energy. The turbines are connected with the armatures of dynamos and electricity is generated. Step-down transformer decreases the voltage.