Is Watt = Volt * Amper?”
When dealing with direct currents (D.C. – the kind that comes from batteries) the answer is yes, Volts * Amps = Watts (except in a few weird special cases). When dealing with alternating currents (A.C. like the kind that comes out of a wall outlet), the answer depends highly upon the load. For what is technically known as a “resistive load” the answer is yes. Examples of resistive loads include portable space heaters without fans, halogen light bulbs, and good old fashioned incandescent light bulbs. For what are known as “reactive loads” the answer is no. Reactive loads get current pushed through them part of the time and store some of this current in addition to the current they consume. During part of the AC cycle, they push this stored current back to the source, creating what is called reactive current. For these loads the power is: Volts * Amps * power factor. Examples of reactive loads include motors (especially powerful motors doing easy work), florescent lights, and certain ele
