# Ohm’s law. # How to Use Ohms Law: Ohms law was found by Georg Ohm and it goes a little something like this:

V = RI

V is voltage, R is resistance and I is current.

The law states that a voltage potential equals the current multiplied by the resistance.

It is used VERY often. It is THE formula in electronics.

You can switch it around and get R = V/I or I = V/R. As long as you have two of the variables, you can calculate the last.

### How to remember Ohms law

A simple way of remembering things is to make a stupid association with it so that you remember it because it’s so stupid.

So to help you remember Ohm’s law let me introduce the VRIIIIIIII! rule. Pretend that your driving a your car really fast, then suddenly you hit the breaks really hard. What sound do you hear?

“VRIIIIIIIIIIII!”

And this way you can remember V=RI ### A practical example

The best way to teach how to use it is by example.

Below is a very simple circuit with a battery and a  resistor. The battery is a 12 volt battery and the resistance of the resistor is 600 Ohm. How much current flows through the circuit? To find the amount of current, we rearrange Mr. VRI and get I = V/R. Now we can calculate the current by using the voltage and the resistance.

I = 12 V/600 OhmI = 0.02 A = 20 mA (milli Ampere)

So the current in the circuit is 20 mA.

If you don’t like calculating things yourself, check out this calculator for Ohm’s law.

### Another example

Let us try another example.

Below we have a circuit with a resistor and a battery again. But this time we don’t know the voltage of the battery. Instead we imagine that we have measured the current in the circuit and found it to be 3 mA (milli Ampere). The resistance of the resistor is 600 Ohm. What is the voltage of the battery? By using our friend VRI we get

V = RI
V = 600 Ohm * 3 mA
V = 1.8 V

So the voltage of the battery must be 1.8 V.

Here is a image to well illustrate Ohm’s Law 