Metric (SI) unit of electrical current. One ampere is the amount of current flowing with an electromotive force of one Volt in a circuit having a resistance of one Ohm. Named after the French mathematician and physicists Andre Marie Ampere who discovered the basic laws of electromagnetism. AMPERE’S FORCE LAW
Ampere’s force law states that there is an attractive or repulsive force between two parallel wires carrying an electric current. This force is used in the formal definition of the ampere, which states that is “the constant current that will produce an attractive force of 2 x 10 Newton per meter of length between two straight, parallel conductors of infinite length and negligible circular cross section placed one meter apart in a vacuum”.
In a series of experiments around 1825 the German Scientist Georg Ohm (1789-1854) demonstrated that there were no perfect electrical conductors. Each type of substance, even the best metals, put up some resistance to the current. Ohm showed that a long wire had more resistance than a short one of the same metal, and thin wires had more resistance than fat ones. Also, in a circuit, the greater the resistance, the more potential difference (volts) was needed to push the current through the wire. The relationship between potential difference, current and resistance and the relationship of voltage, resistance and current in electrical circuits, it is the most powerful law in the study of electronics become known as Ohm’s Law.
Ohm’s practical experiment showed the mathematical links between resistance, potential difference, and current. Ohm’s law of 1826 states that provided the temperature does not change, the current flowing through certain conductors is proportional to the potential difference (voltage) across it.