The mechanical equivalent of heat states that motion and heat are mutually interchangeable and that in every case, a given amount of work would generate the same amount of heat, provided the work done is totally converted to heat energy. In this experiment, instead of mechanical motion, resistive heating is used. A known amount of current (\(I\)) is passed through a wire whose ends are maintained at a constant potential (\(V\)). The electrical energy supplied in time \(t\) is – $$ E_{electrical}=VIt$$ This energy leads to an increase of temperature (\(ΔT\)) of a known amount of water (\(m_{w}\)). The energy required for this rise is supplied by Eelectrical and is equal to – $$E_{WaterHeat}=m_{w}c_{w}T$$ As the water is taken in a container (here copper of mass \(m_{c}\)), also there will be an increase its temperature. The energy required for this rise is also supplied by Eelectrical and is equal to – $$E_{CopperHeat}=m_{c}c_{c}T$$ Electrical energy (in Joules) = heat energy (in calories) $$VIt=m_{w}c_{w}T + m_{c}c_{c}T$$