Given, Heat energy, H1=500J Initial current, I1=1.5A, final current, I2=3A and time, t=20s According to Joule's law of heating, H=I2Rt ⇒H1=l12Rt.....(i) and H2=I22Rt....(ii) [ Resistance and time being the same in both cases] Dividing Eq. (i) by Eq. (ii), we get ⇒