Ohm's Law

Ohm's Law describes the relationship between Voltage, Current (intensity) and Resistance as follows in the formula below.

Formula explaining Ohm's Law. The current I in amperes is equal to the voltage V in volts divided by the resistance R in ohms.

Figure 1. Ohm's Law Formula

Each variable depends on the other two. This means that if we know any of the two variables we can calculate the third one. This means, for example, that the resistance of a resistor will condition the current and the voltage of the electric current moving through it.

For details on how to apply this to series and parallel resistors follow the links.

Not all materials in nature follow Ohm's Law. From Ohm's Law, we can deduct that for a given resistance (R), the current is proportional to the voltage applied. Some materials don't follow this rule and the current may not follow a linear relationship with the voltage applied. Materials that follow Ohm's Law are called Ohmic Materials, while materials not following Ohm's Law are called Non-Ohmic Materials.