EM weapon

An EM (or electromagnetic) weapon was a type of weapon which operated on the principle of electromagnetism.

The EM-33 pistol was the standard issue EM side arm used by Earth's Starfleet officers and Earth Cargo Service personnel during the mid-22nd century. By 2151, the EM weapons fell out of use aboard Starfleet vessels in favor of the phase weapons. The disadvantages of EM weapons was the need to compensate for particle drift and having no stun setting. 

Electromagnetic pulses had tactical applications as well. They could be used to disable weapons, disrupt detection grids, jamm communications and trigger destructive solar plasma ejections.