railgun

thumb|285px|Test firing at the United States Naval Surface Warfare Center Dahlgren Division in January 2008. The fireball is a result of pieces of the projectile shearing off during launch and igniting mid-air.

A railgun or rail gun, sometimes referred to as a rail cannon, is a linear motor device, typically designed as a ranged weapon, that uses electromagnetic force to launch high-velocity projectiles. The projectile normally does not contain explosives, instead relying on the projectile's high kinetic energy to inflict damage. The railgun uses a pair of parallel rail-shaped conductors (simply called rails), along which a sliding projectile called an armature is accelerated by the electromagnetic effects of a current that flows down one rail, into the armature and then back along the other rail. It is based on principles similar to those of the homopolar motor.