Electromagnetic Pulse Bomb: Does It Really Destroy All Electronics?

The lights suddenly go out, the mobile network is disrupted, computers shut down, and modern technological devices simply become unusable. This is how electromagnetic pulses, or EMPs for short, are often portrayed in films—but is this really what happens?

What is an electromagnetic pulse?

An electromagnetic pulse is a very short burst of electromagnetic energy. When a rapidly changing electromagnetic field reaches a conductive material—such as an electrical wire or antenna—it induces voltage and creates an electric current in it. If this surge is too strong, electronic equipment may malfunction.

We are also familiar with a similar phenomenon on a smaller scale from everyday life. A lightning strike or a strong electrostatic discharge can also cause overvoltage and damage electronic equipment.

What is an “EMP bomb”?

“EMP bomb” is an everyday term that does not refer to one specific type of weapon.

Basically, we can speak of two categories:

• nuclear electromagnetic pulse
• non-nuclear, locally acting electromagnetic pulse

Nuclear EMP

Many people do not know that a nuclear explosion produces not only heat, a shock wave, and ionizing radiation, but also an electromagnetic pulse. In addition, a nuclear EMP generated at high altitude can disrupt electrical equipment over a very large area.

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Non-nuclear EMP weapons

An electromagnetic pulse can also be generated without a nuclear explosion. Such devices are often referred to as high-power microwave, or HPM, weapons.

They typically have an effect over a smaller area and against specific targets, such as transmission towers, radars, or drones.

Contrary to what is shown in films, however, it is unlikely that a small device could shut down the electronics of an entire country at once. Achieving an effect over a large area would require an enormous amount of energy and special conditions. At the same time, HPM weapons may be capable of disrupting or damaging communications equipment, radars, drones, and other electronic systems over a smaller area.

Misconceptions

“EMP directly kills people”

An electromagnetic pulse primarily poses a threat to electronic systems. In the case of a nuclear explosion, the explosion itself, the heat, and the ionizing radiation can of course pose an immediate threat to life, but this is not the effect of the EMP.

“After an EMP, all electronics are permanently destroyed”

The effect depends on the device and the circumstances. Some systems may suffer permanent damage, others may only malfunction temporarily, while still others may remain operational.

“There is no protection against EMP”

There is limited protection against EMP, but the level of protection depends on how strong the pulse is and what its source is. The most effective forms of protection are:

• Disconnecting electronic devices from the grid: Unplugged devices may be less vulnerable in some cases because they are not connected to long electrical or data cables that can collect electromagnetic energy like antennas. However, against a very strong pulse, unplugging a device alone does not necessarily provide complete protection.
• Faraday cage: a space enclosed by metal mesh or metal sheets that protects the objects and living beings inside it from external electromagnetic effects. The metal covering conducts the electric field away, so the inside of the cage becomes shielded. A shielding effect similar to that of a Faraday cage can also be observed in everyday life, for example in the metal body of a car or an aircraft, although these do not provide complete protection at every frequency and under every condition, or in the case of a microwave oven, whose glass door contains visible metal mesh designed to keep microwaves inside the appliance. A Faraday cage is frequency-dependent and only works properly if it has no gaps or unprotected cables running into it.
• Surge protection: Properly installed surge protection devices can also help protect against overvoltages caused by smaller electromagnetic disturbances.