Question

State Joule’s law of heating and give its mathematical form. An electric iron tak es a current of 5A and develops 1.5 ×10⁴ J of heat energy in 30s. Calculate the resistance of the electric iron

Answer 1

According to the Joule’s law of heating, heat produced in a resistor is directly proportional to the:
(i) square of current for a given resistance
(ii) resistance for a given current and
(iii) the time for which the current flows through the resistor. Mathematical form : H = I²Rt