De wet van Ohm

In 1827, a German physicist, Georg Simon Ohm, demonstrated Ohm's law experimentally.

Ohm's law states that the current passing through a material is directly proportional to the voltage across the device under constant surrounding conditions.

Any material that obeys Ohm's law is known as an ohmic material, whereas if it does not obey Ohm's law, it is known as a nonohmic material.

Consider another experimental setup to demonstrate Ohm's law, consisting of a resistor, power supply, switch, voltmeter, and ammeter. The voltage across the resistor is measured using a voltmeter, while the current in line with the resistor is measured using an ammeter.

When the resistor is connected to the power supply, the current flows in the clockwise direction, and the voltmeter and ammeter show positive readings. Conversely, when the leads of the power supply are switched, the current flows in the counterclockwise direction, resulting in negative readings.

A graph plotted between the voltage and current readings is found to be linear. The slope of the line gives the resistance, confirming the resistor to be an ohmic device.