what is watts
The watt (symbol: W) is a derived unit of power in the International System of Units (SI), named after the Scottish engineer James Watt (1736â1819). The unit is defined as joule per second and can be used to express the rate of energy conversion or transfer with respect to time.It has dimensions of L 2 M T â3.or example, when a light bulb with a power rating of 100W is turned on for one hour, the energy used is 100 watt hours (WÂ·h), 0.1 kilowatt hour, or 360 kJ. This same amount of energy would light a 40-watt bulb for 2.5 hours, or a 50-watt bulb for 2 hours.