Re: Physics(Electricity) by Srinath Murthy - Sunday, 12 September 2010, 2:23 PM Number of replies: 0 The resistance of the kettle remains the same at 200 V and at 220 V. Power is proportional to V2 in such case.Elec. Energy, (500 x 2202/2002) x 30 = Heat Transfer, 0.4 x 4200 x Delta TYou should be able to find Delta T from the above. Permalink Show parent Reply