Electrical Power (VI)

This formula tells you how much electrical energy a component uses or turns into heat, light, motion, or other forms each second. It works because voltage is the energy supplied to each coulomb of charge, and current is the rate at which charge flows, so multiplying them gives energy per second, which is power. A larger voltage, a larger current, or both will increase the power.

Use this when you know the voltage across a device and the current through it and want to find how much power it uses. It is common in circuit analysis for resistors, lamps, motors, chargers, and any electrical component.

• Using voltage in volts and current in milliamps without converting the current to amps
• Confusing power with energy; power is the rate of using energy, not the total energy itself
• Using the wrong current value, such as the total circuit current when the formula requires the current through the specific component