On Fri, 4 Aug 2006 13:47:26 +0100 , "Ken Walker" said: > It's always confused me sometimes. > > My example of confusion. You have your units wrong, I think... > A 100 watt bulb, now i know watt is watts/second, so does a 100w bulb use > 100w/second or 6000 w/min or 360,000 w/s. Well if it did it'd be well > beyond > my income to pay for a single bulb yearly. It's not watts per second. For electricity billing, its kW * hours. 1 kwh = 1000W * 3600 seconds = 3 600 000 Joules. You're paying for energy used, not for power. Watts are already Joules/second, it would make no sense to use Watts/second which would be watts per second squared. (an acceleration of energy consumption?) It's a bit the same confusion people have with mAh (battery capacity), they are *NOT* milliamps per hour, they are mA *multiplied* by hours. Christian -- CSB csb_cbw@fastmail.fm -- http://www.fastmail.fm - Email service worth paying for. Try it for free -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist