# Ohm’s Law and Power

Electricity has three primary parameters: voltage, current, and resistance.

Ohm’s Law represents the relationship between the three parameters.

Let’s define the three primary parameters.

**Electric voltage** is the difference in electric potential energy between two points per unit electric charge. It is measured in Volts, which are equal to a joule of energy per coulomb of charge.

**Electrical current** is a flow of electric charge. It is measured in amperes, or amps., which are equal to a flow of one coulomb of charge per second.

**Electrical resistance** is the measure of how difficult it is to pass an electric current through a conductor. It is measured in Ohms, which are equal to a volt per ampere.

So, we know that these three are related, but how they are related is where we find our equation:

Ohm’s law states that current is directly proportional to voltage. So, from this we derive the equation R=V/I. Where V is voltage, I is current, and R is **resistance**. Getting each variable by itself on one side of the equation allows you to solve for each variable.

So, that’s Ohm’s law. Now, let’s take a look at power.

Electrical power can be defined as the rate, per unit of time, that an electrical circuit transfers energy. If you really wanted to break it down, you could just say that electrical power is the rate of doing work. Power is measured in Watts, which are equal to a joule of energy per second.

The equation for electrical power is P=IV.

Where P is electrical Power, I is current, and V is voltage.

If you multiply power by time this will give you the total **energy**, which is generally given in kilowatt-hours. The power equation and the Ohm’s law can be combined to produce P=V^2/R and P=I^2R.

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