The following formula calculates the power used by any electric device.




For example:
An ordinary light bulb, (100Watt) uses in 1 hour:
100Watt * 1 Hour = 100Wh (Watt Hours)

While an "economical" one of 15 Watt uses in 1 hour:
15Watt *1 Hour = 15 Wh (Watt Hours)





Power         *     Hours of use      =   Energy
(the  Watt)    (multiplied)
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