Question: how much energy do you need to heat water?
Answer: What c in the equation is, the specific heat capacity. So in water it takes 1200 joule's to raise a Kg of water by 1 degree K or in degrees C. If this takes 1 min to boil the power required to boil the water equals 96kilo joules/60 seconds =1600 watts or 1.6 kilo watts.