Power
Power = energy per unit time
Unit: Watt = 1 Joule per second
Light bulb - typical 100 watts = 100 joules/sec Heaters, etc, quoted in kilowatts
Often Energy is quoted in kilowatt hours = 103 joules/sec x 3600 sec = 3.6 x 106 joules
(Costs about $0.10 – cost of 10 light bulbs for 1 hour)