EMP (Electro-Magnetic Pulse)

An electromagnetic pulse is a short burst of electromagnetic energy. Its shortness means that it will always be spread over a range of frequencies. Pulses are typically characterized by the type of energy (radiated, electric, magnetic or conducted), the range or spectrum of frequencies present, and the pulse waveform (shape, duration, and amplitude).

EMP interference is either disruptive or damaging to electronic equipment, and at higher energy levels a powerful EMP event can damage objects such as buildings and other structures. The damaging effects of high-energy EMP have been used to create EMP weapons. These are typically divided into nuclear and non-nuclear devices.

At a high voltage level an EMP can induce a spark, for example from an electrostatic discharge (ESD) when fueling a gasoline-engine vehicle. These sparks are known to cause fuel-air explosions. A large and energetic EMP can induce high currents and voltages in a target, damaging electrical equipment or disrupting its function. A very large EMP event, lightning strikes for example, are capable of damaging objects such as trees, buildings and aircrafts, either through heating effects or the disruptive effects of the very large magnetic field generated by the current. An indirect effect can be electrical fires caused by heating. Most engineered structures and systems require some form of protection against lightning to be designed in them.

Types of military EMPs include:
 * Nuclear electromagnetic pulse as a result of a nuclear explosion. A variant of this is the high altitude nuclear EMP which produces a pulse with a larger amplitude and different characteristics due to interactions with the Earth's magnetic field.
 * Non-nuclear electromagnetic pulse weapons.