The concept of inductance is important in the study of electronics and electromagnetism. The discovery of this idea was observed independently by two scientists: Joseph Henry for self-inductance and Michael Faraday for mutual inductance. Thanks to the principle of inductance, the operation of electric generators is possible today.
To define it simply, inductance is the property of a conductor that is evident when there is a change in the current flowing through the conductor. Every time this change in current happens, there is a creation (induction) of electromotive force (voltage) in the conductor (self-induction) or a nearby conductor/s (mutual inductance).
The effects of induction were derived from two physics observations: Oersted’s law (a current generates a magnetic field), and Faraday’s law of induction (a magnetic field is able to induce voltage even in conductors nearby). In another law, the Lenz’s law, the changing electric current that runs through a circuit that contains inductance, induces a proportional voltage that is able to oppose any change in current. If the same circuit where the current runs through is the only one affected, that is called self-inductance. If there is a varying magnetic field, and the circuit induces a force in nearby circuits – that is called mutual inductance.
Faraday discovered electromagnetic induction after he conducted an experiment involving two coils of wire that were wound on opposite sides of an iron ring. The coils were not connected to each other. Coil A was attached to a battery while Coil B was attached to a compass that served as the galvanometer in detecting the flow of current. The experiment showed that when the switch was closed, a current ran through Coil A and it caused the iron ring to become magnetized. It was also observed that when the switch was first closed, the compass deflected briefly – signifying that Coil B was affected briefly by an electromotive force. When the switch was opened, the same deflection happened to the compass but this time, in the opposite direction.
Faraday hypothesized that opening and closing the switch can cause the magnetic field to change. It was this change that caused the current to be induced in the second coil. This induction can happen in two ways: when the coil is moved near a permanent magnet or the magnet is moved towards a stationary coil.
It is important that a change in magnetic flux must occur for the induction to happen. Without the change, there is no inductance taking place.
Related Article:
Joseph Henry (1797-1878): The Electromagnetic Phenomenon
Voltage In A Battery : We Need It To Be Constant