Digital Clocks & Electromagnetic Pulses

An electromagnetic pulse (EMP) is an intense, short burst of energy that can damage or destroy electrical circuits in a wide area. Devices containing microchips, such as digital clocks, are particularly vulnerable to damage from an EMP.

Causes

Electromagnetic pulses can be caused by the detonation of a nuclear explosive high in the atmosphere (at lower altitudes, denser air limits the spread of radiation). Some other devices can produce similar effects on a smaller scale.

Effects

The burst of energy from an EMP causes a sudden power surge in any electrical circuits within a wide area (depending on the size and design of the device). Delicate systems like microchips, which are particularly sensitive to such surges, can be damaged or destroyed by the burst.

Digital Clocks

Digital clocks contain microchips, making them vulnerable to serious damage from an EMP. Even if the clock is not destroyed, the power surge may cause it to reset. Spring-based clocks would be completely unaffected by an EMP.

Protection

While it is difficult to defend against an EMP, a study conducted by the U.S. Marine Corps determined that it is possible to protect against an EMP attack. Circuits can be designed to be resist sudden power surges and ready access to replacement parts can make a quick recovery possible.

Natural EMPs

As well as explosives, there is a possibility of a natural electromagnetic pulse caused by a large solar flare striking the Earth's magnetic field.

References

• Congressional Research Service Reports: High Altitude Electromagnetic Pulse (HEMP) and High Power Microwave (HPM) Devices: Threat Assessments
• U.S. Army Corps of Engineers: Electromagnetic Pulse and Tempest Protection for Facilities
• GlobalSecurity.org: Electromagnetic Pulse - From Chaos To A Manageable Solution