http://en.wikipedia.org/wiki/Interferometry
Food control
http://en.wikipedia.org/wiki/Capacitor
http://en.wikipedia.org/wiki/Transformer
E.g. http://en.wikipedia.org/wiki/Magnetic_resonance_imaging
Rotary Magnetic Position Sensors
http://en.wikipedia.org/wiki/Ferrofluid
Creating solar energy
http://en.wikipedia.org/wiki/Voltage_source
