A refrigeration unit removes heat at the rate of 1200Js−1 from a cold chamber kept at 270K. Its coefficient of performance as a refrigerator is 6.
(a) Find the electrical power that must be supplied to drive the unit.
(b) If the same machine is switched to operate as a heat pump between the same reservoirs, calculate the rate at which it can deliver heat to the 300K room using the power obtained in part (a).
(c) An electric resistance heater converts all supplied electrical power into heat. Compare the heat obtained per second from the heat-pump operation with that from an electric heater using the same power input, and state the percentage increase.