The experiment to explore the relationship between current and voltage has ohm's law. The ohm's law of the experiment of the relationship between current and voltage is that in the same circuit, the current passing through a conductor is directly proportional to the voltage at both ends of the conductor and inversely proportional to the resistance of the conductor. This law was put forward by georg simon ohm, a German physicist, in his paper Determination of the Law of Metal Conductivity published in April 1826.

With the development of circuit research, people gradually realize the importance of ohm's law, and ohm's reputation is greatly improved. In order to commemorate ohm's contribution to electromagnetism, the unit of resistance is named ohm in physics, which is represented by the symbol ω. In the experiment, the resistor is equivalent to an electrical appliance. When using rheostat, it is best to connect a fixed resistor in series. Otherwise, when the rheostat is set to 0, the circuit is short-circuited.

The first stage of ohm experiment is to explore the relationship between the electromagnetic force attenuation caused by current and the length of wire. The results were published in his first scientific paper 1825 in May. In this experiment, he met with the difficulty of measuring the current intensity.

Inspired by the galvanometer invented by German scientist Schveger, he combined Oster's discovery of current magnetic effect with Coulomb torsion balance method, designed a current torsion balance, and used it to measure current intensity.