What is an Electro Magnetic Pulse(EMP)?

An electromagnetic pulse is a burst of electromagnetic energy in the atmosphere, considered capable of widespread damage to power lines, telecommunications, and electronic equipment. There is no danger to cars from EMP. A high altitude EMP can last several hours or even days, if the EMP has ionised atmospheric particles and molecules. A powerful EMP can also directly affect magnetic materials and corrupt the data stored on media such as magnetic tape and computer hard drives.