Question

what is joule's law ?

Answer 1

JOULE'S LAW:-

Joules law states that the heat produced in a conductor by a constant current is equal to the product of the square of the current and resistance of the conductor and the duration of time the current passes. 
That is, Q = I2 × R ×t, 

where, Q is the heat produced in joules,

 I is the current through the conductor in amperes, 

R is the resistance of the conductor in ohms and, 

t is the time in seconds.

HOPE IT'S HELPFUL ☺

Answer 2

Heat produced in a conductor is proportional to square of amount of current, resistance and time i.e
H=I^2 .R.T