another one
source:popularmechanics.com
Electricity may protect tanks more effectively than steel, ceramics or outward-exploding reactive armor. Army scientists are investigating two technologies. Both use a fiberoptic sensor to detect when a round has struck, and then respond by turning on electricity. In one approach, the current alters the thickness of a special shape-memory alloy, thereby increasing its resistance to penetration. The second method, shown above, uses electricity to create a powerful magnetic field. The magnetic force pulls apart the concentrated jet of metal created when a round strikes a tank's armor. Instead of streaming into the tank, the molten metal expands and dissipates harmlessly. Specifics of both projects remain classified.
