The amount of Power consumed by a device or drained from a generator is proportional to the product of the amount of current flowing through the device by the applied voltage.

**Formula 1 **

P = V x I

**Where: **

P is the Power in watts (W)

V is the voltage in volts (V)

I is the amount of current (intensity) in amperes (A)

**Derivated Formulas **

**Formula 2: **

V = P/I

**Formula 3: **

I = P/V

**Application Example: **

Calculate the dissipated power by a resistor where a current of 200 mA flows when it is plugged to a 12 V power supply?

**Data: **

V = 12 V

I = 200 mA = 0,2 A

P = ?

**Applying formula 1:**

P = 12 x 0,2 = 2,4 W (or joules per second)