Mutuallinduktivität

Mutuallinduktivität, often denoted by the symbol M, describes the phenomenon where a changing current in one circuit induces a voltage in a nearby circuit. This induction occurs due to the magnetic field produced by the first circuit linking with the second circuit. The magnitude of the induced voltage is directly proportional to the rate of change of current in the first circuit and the mutual inductance between the two circuits.

The unit of mutual inductance is the henry (H), named after the American physicist Joseph Henry. Mathematically, the induced electromotive force (EMF), denoted by ε, in the second circuit can be expressed as ε₂ = -M * (dI₁/dt), where dI₁/dt is the rate of change of current in the first circuit. The negative sign indicates that the induced current opposes the change in magnetic flux, according to Lenz's Law.

Mutual inductance depends on the geometry of the two circuits, such as their size, shape, and relative orientation, as well as the magnetic permeability of the medium between them. Two coils placed close together with their magnetic fields strongly coupled will have a high mutual inductance. Conversely, if the coils are far apart or their magnetic fields do not overlap significantly, the mutual inductance will be low. This principle is fundamental to the operation of transformers, where mutual inductance is used to transfer electrical energy between circuits. It also plays a role in the design of inductors and other electromagnetic devices.