# Ohm's law

Ohm's law says that in an electrical circuit, the current passing through a resistor between two points, is related to the voltage difference between the two points, and inversely related to the electrical resistance between the two points. This relation is shown in the following formula:

$R = \frac VI$

Where I is the current in amperes, V is the potential difference in volts, and R is a constant, measured in ohms, called the resistance.

Also says that current is directly proportional to voltage loss through a resistor. That is if current doubles then so does voltage. To make a current flow through a resistance there must be a voltage across that resistance. Ohm's Law shows the relationship between the voltage (V), current (I) and resistance (R). It can be written in three ways:

$I = \frac{V}{R} \quad \text{or}\quad V = IR \quad \text{or} \quad R = \frac{V}{I}$.