Magnetic Induction (Electromagnetic Induction) is the creation of a voltage across an expanse of electrically conductive material caused by a change in a surrounding magnetic field. It is a consequence of Maxwell's Equations (specifically, Ampere's Law) and is the basic mechanism of electrical generators and a key part of electrical transformers.
Magnetic induction occurs in astronomical phenomena when a magnetic field is changing (e.g., a rotating object with a magnetic field misaligned with the axis of rotation) and can also occur when a conductive material is moving through a magnetic field. It is also a key part of Magnetohydrodynamics.
Magnetic induction has been used as a means to detect subsurface water in solar system Moons: if the host planet has a misaligned magnetic field and the moon's subsurface water is conductive (e.g., salty), a voltage is induced in the water, which, in turn, modifies the surrounding magnetic field, potentially beyond the surface of the moon. This gives one means an external probe can provide evidence of the internal characteristics of the moon. Europa is an example.
The term Magnetic Induction is also sometimes used as a synonym for the related measure, Magnetic Flux Density.
Magnetic Flux Density (B)