What is Electromagnetic Interference?

Mary McMahon
Mary McMahon

Electromagnetic interference (EMI) is a common problem which occurs with electronic devices when the performance of a device is disturbed or interrupted by electromagnetic radiation or conduction. The source of EMI can be natural or artificial in origin, and it can become a very serious problem in some situations. In addition to appearing accidentally, electromagnetic radiation can also be created deliberately, as is done by military aircraft which wish to jam the electronic signals of enemy forces.

Energy-guzzling objects, such as refrigerators, can create interference with other household electronics.
Energy-guzzling objects, such as refrigerators, can create interference with other household electronics.

Solar flares and the Northern Lights are two common natural causes of electromagnetic interference. Both of these phenomena cause radiation which can interfere with electronic devices. Many people with radios have noted that sometimes the signal experiences a profound decline in quality as the result of increased solar activity, making it difficult to hear radio stations through static and other signal interruptions. Solar activity can also disrupt the function of satellites and aircraft.

Cordless phones can cause electromagnetic interference.
Cordless phones can cause electromagnetic interference.

Any electronic device can potentially create interference. They may cause narrowband or broadband interference which can do everything from creating wiggles on a television screen to causing phone calls to be heard over baby monitors. Wireless devices like cell phones, cordless phones, and wireless Internet routers in particular tend to be prone to generating electromagnetic interference. Anything which draws large amounts of energy, like a refrigerator or air conditioner, can also be responsible for interference.

Solar flares may disrupt the operations of radio telescopes, which detect radio waves, a form of electromagnetic radiation, from space.
Solar flares may disrupt the operations of radio telescopes, which detect radio waves, a form of electromagnetic radiation, from space.

Manufacturers of electronic devices must usually conform with regional laws which are designed to prevent electromagnetic interference. These measures include proper grounding of electrical circuits, and shielding of devices so that they will be less prone to emitting radiation. People may also be required to use dedicated circuits for particular devices, both as a safety precaution and to reduce electromagnetic conduction between these devices and devices on the same circuit.

Terrorists may build jammers for the purpose of blocking signals or interfering with the function of electronic devices.
Terrorists may build jammers for the purpose of blocking signals or interfering with the function of electronic devices.

Before they are sold, electronic devices are usually tested for compliance with laws regarding electromagnetic radiation. People can reduce the amount of EMI they experience in their homes and businesses by keeping items which are likely to cause interference isolated, and making sure that devices are used as directed. Computers, for example, should be left shielded in their cases.

The northern lights are a common cause of electromagnetic interference.
The northern lights are a common cause of electromagnetic interference.

The deliberate generation of electromagnetic interference is a tactical tool utilized by some law enforcement agencies and militaries for the purpose of jamming signals. Individuals such as criminals and terrorists may also build jammers for the purpose of blocking signals or interfering with the function of electronic devices.

Electromagnetic shielding is most often employed to protect something or someone against radio waves.
Electromagnetic shielding is most often employed to protect something or someone against radio waves.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments

SilentBlue

These waves are often the reason that we are able to communicate from a long distance and hear things from the other side of the world. Skype and audio visual channels of interaction are kept safe and travel at light speed due to the interaction of visual and audio waves with electromagnetic waves. Disturbances in these waves can cause them to be disrupted and inconsistent.

JavaGhoul

EMI shielding is used for important police and military signals which are not to be intercepted or tampered with. EMI can cause death and accidents for people who are depending on the transmission of important information.

Renegade

Auroras and static are all normal electromagnetic readings. If you were to turn on a radio back before radio waves were discovered, you would hear pure static. Today, this static has been manipulated for sound traffic generated by humans. When this traffic is interfered with by other humans, speaking on the same wavelength, you get mixed signals and static.

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