Power is the term used to define the rate of electrical energy consumption. Electrical energy provides light, runs motors, heats homes, operates TV's, and computers and many other appliances. The basic unit of measurement of electrical energy is called the watt. It is calculated using the equation:

P = I ´ E

Where

P = Power in watts
I = Current in amps
E = Voltage in volts

A 12 volt battery is pushing 3 amps through a light bulb that is producing light.What is the power rating of the bulb ?

P = I ´ E

P = 3 amps ´ 12 volts

P = 36 watts. The bulb is a 36 watt bulb.

If you know the power and one other element in the equation, you can find the third element

You have a circuit with 10 volts applied to a 20 watt motor. What is the current in this circuit ?

Estimate the answer:

Less than 3 amps
Between 3 and 5 amps
Over 5 amps