AC voltage varies between maximum positive voltage

and maximum negative voltage in a continous fashion

as shown by the sine wave above. In a 120 volt

system, the voltage ocillates from 0v to +169.7v to 0v

to -169.7v to 0v and so on. This generates the 120 volts

(120v RMS) that we are all familiar with.

AC Power as expressed in Watts is the product of volts

multiplied by amps (P = V x I). The wave form above

represents this product.

(Remember that a (-V) x (-I) = (+W).

As you can see, the Power varies from 0w to 2,400w

in this example. Peak power, at the top of the curve,

is 2,400w, and this power level lasts for only an

instant. Average power or real power will be 1,200 watts,

1/2 the peak power.