electromagnetic pulse (EMP)

An electromagnetic pulse (EMP) is an intense burst of electromagnetic (EM) energy caused by an abrupt, rapid acceleration of charged particles, usually electron s. An EMP can contain energy components over a large part of the EM spectrum , from very-low-frequency ( VLF ) radio to ultraviolet ( UV ) wavelength s.

A lightning strike produces a localized EMP that gives rise to large electrical current s in nearby wires. A single current surge can damage sensitive hardware such as computers and peripherals. All electronic and communications systems should have some form of protection against the effects of an EMP. Transient suppressors, also called surge protector s, AC outlets, and modem jack s offer limited protection against the EMPs that occur during thundershowers. The best method of protection is to unplug AC cords and modem lines of computers when they are not in use.

The detonation of a hydrogen bomb at a high altitude generates a powerful EMP over a large geographic area. This induces damaging electrical currents in wireless antennas, telephone lines, and utility wires. A strategic nuclear weapon used in this way, for the purpose of disrupting the communications and/or electrical infrastructure, is called an electromagnetic bomb .