Watt

The watt is the SI unit of power and is equal to 1 joule per second. Named after James Watt, Scottish engineer (1736-1819) and pioneer in steam engine design.

It is useful to have some examples, even if some of these are a bit out of the ordinary:

  • 2.5×10-15 W = minimum discernible signal at the antenna terminal of a good FM radio receiver
  • 1.0×10-12 W = average power consumption of a human cell
  • 2.0×10-9 W = power consumption of 8-bit PIC chip in “sleep”
  • 1.0×10-6 W = approximate consumption of a quartz wristwatch
  • 5.0×10-3 W = laser in DVD drive
  • 7 W = typical household LED light bulb
  • 100 W = approximate basal metabolic rate used by the human body
  • 3000 W = heat output of a domestic electric kettle
  • 75,000 W = Family car (100PS)
  • 16×106 W = rate at which a typical petrol pump transfers chemical energy to a vehicle
  • 2.074×109 W = peak power generation of Hoover Dam
  • 3.9×1026 W = Sun energy production