(i) Give the SI unit of power. (ii) What is the commercial unit of energy ? (iii) An electric heater is rated 1500 W. How much energy does it use in 10 hours?


#1

SI unit of power is watt.
1 unit = 1 kilowatt hour
Given, power, P = 1500 watt = 1.5 kW
Time, t = 10 hour
Energy = power x time = 1.5 x 10 =15 kW h
Energy consumed by the heater = 15 kW h = 15 units