An immersion heater marked 1000 W, 220 V is used to warm water in a bucket.
a. (i) Calculate the resistance of the heating element when it is at its operating temperature.
b. (ii) The heater is placed in 4 kg of water initially at 25∘C. Assuming that 90% of the electrical energy supplied is actually absorbed by the water, determine the time required for the water temperature to reach 90∘C. Take the specific heat capacity of water as 4.2kJ kg−1∘C−1.
c. (iii) Express the electrical energy drawn from the mains during the heating period in kilowatt-hour (kWh).