The
EMP, or
Electromagnetic pulse, is a rapid magnetic fluctuation which induces pulses of current in unshielded electronics. Natural sources of EMP include lightning, whereas artificial ones include a
nuclear blast.
A nuclear blast generates an EMP via gamma radiation interacting with air molecules to create Compton electrons. These create a brief current and an associated
electromagnetic pulse. This is especially hazardous with an exo-atmospheric nuclear blast outside the atmosphere, as the region affected by Compton electrons in such a manner becomes enormous and the electrons will rotate around the Earth's natural magnetic field lines, creating a vast pulse.
EMPs and NEMPs are extremely hazardous to unshielded electronics, causing rapid fluctuations in current, especially in long wires or antennae.