The microprocessor readsa one or zero by detecting the flow of electrons between the magnetic layers of each sandwich.

FORBES: Total Recall

When something that conducts electricity sweeps through a magnetic field, a current starts to flow through it (this is the basis of a dynamo).

ECONOMIST: Here be serpents

To study the neurology of tickling, Dr Blakemore and her team stuck volunteers into a magnetic-resonance-imaging machine (which monitors oxygen flow to the brain, and thus indicates the amount of activity in that organ's various parts).

ECONOMIST: Neuroscience: Tickled curiosity | The

Such a thin layer alters the current flow in a way that reduces the current's susceptibility to magnetic interference.

ECONOMIST: Superconductors are starting to become useful

The Sun's changeable magnetic field is generated at the boundary between these two layers, where strong electric currents flow.

BBC: Sun, Trace