By Evan Ackerman
Electromagnets can be used by people with too much time and electrical knowledge to crush cans, but the truly ambitious can (briefly) harness a magnetic field to shrink a quarter to about half its original size. The principle is kinda simple, really… A big capacitor sends a surge of electricity into a coil around a quarter. This creates a magnetic field in the coil, and also in the quarter, but the field in the quarter has the opposite polarity. The quarter tries to get away from the coil, but having nowhere to go, shrinks inward as the magnetic field strength exceeds the strength of the metal. The coil, on the other hand, explodes outward at mach 2. The process takes between 30 and 40 microseconds, meaning that the edges of the quarter shrink inward at about 400 mph.
This particular experiment was done by Hackerbot Labs, and Intellectual Ventures has more pics and video at the link below.