Ans. JOULE'S LAW
The amount of energy generated in a resistance due to the flow of charges is equal to the product of square of current, resistance and the time duration.
Consider two points with a potential difference of V volts. If one coulomb of charge passes between the.se points; the amount of energy delivered by the charge would be V joules. Hence, when Q coulomb of charge flows between these two points, then we will get QV joules of energy. If we represent this energy by W, then
Electrical energy supplied by Q charge W = QV joules
Now current, when charges Q flow in time t, is defined as
or Q = It So
Energy supplied by Q charges W = V x I x t
This electrical energy can be converted into heat and other forms in the circuit.
From Ohm's law, we have
V = IR Thus
V2t Energy supplied by Q charges W = I2 R t = ~p-
This equation is called Joule's law.