What Causes Electric Magnetic Fields?

Electromagnetic fields (EMFs) are invisible lines of force that surround any electrical device. They are created by the interaction of electric and magnetic fields. Though electromagnetic fields are naturally present, the widespread use of electricity in modern society has greatly increased exposure to man-made EMFs from power lines, wiring, and electrical appliances.

Understanding what causes EMFs is important because some studies have linked prolonged exposure to high levels with potential health effects like neurological problems and cancer. However, the research is still inconclusive on risks from typical daily exposure. While more studies are needed, people may want to take reasonable precautions around strong EMF sources. This article will examine the physics of electromagnetic fields and what creates them both naturally and artificially.

Electric Fields

Electric fields are created by electric charges. Atoms and molecules contain positive and negative charges, with the nucleus made up of positively charged protons and neutral neutrons, while electrons orbit the nucleus carrying a negative charge. The movement and separation of these charged particles creates an electric field.

Specifically, electric fields are produced by voltage differences between two points, known as electric potential. Voltage, which is measured in volts, refers to the amount of potential energy between two charges. The greater the voltage difference between two points, the stronger the electric field. This field acts as a force on other charges in the area, either attracting or repelling them depending on whether the charges are opposite or similar.

For example, the buildup of negative charge on a storm cloud and positive charge on the ground creates an electric field that manifests as lightning when the voltage difference becomes great enough. Static electricity is another everyday example of electric fields, where charge builds up on surfaces through contact and separation, creating small electric sparks when discharge occurs. Overall, electric fields permeate our environment and exert forces on charged particles as voltage differences fluctuate.

Magnetic Fields

Magnetic fields are invisible fields generated by moving electric charges that exert magnetic forces. They are produced by permanent magnets or electric currents. Permanent magnets, like those found on your refrigerator, produce constant magnetic fields. These fields enable the magnet to stick to metal objects.

Electric currents in things like power lines or electronics also generate magnetic fields. This occurs because the flow of electric charges in a current creates a force that spins the charges to produce a magnetic field that circles around the wire carrying the current. The strength of the magnetic field depends on the amount of current – higher electric currents produce stronger magnetic fields.

The direction of the magnetic field produced by a current-carrying wire depends on the direction of the current flow. The field circles around the wire in a direction determined by the right-hand rule. If you point your right thumb in the direction of the current, your fingers will curl around the wire in the same direction as the magnetic field.

Strong magnetic fields from sources like MRI machines, transformers and powerful magnets can be hazardous if proper precautions aren’t taken. But the magnetic fields produced by things like power lines, electrical wiring and appliances quickly decrease with distance and are too weak to cause health effects.

Electromagnetic Fields

Electromagnetic fields are generated by the interaction between electric and magnetic fields. Electric fields are produced by voltage or electric potential difference, while magnetic fields are created by electric current or charge in motion. When electric charges accelerate, they produce magnetic and electric fields that oscillate perpendicular to each other. This generates electromagnetic waves that can propagate through space.

The interplay between oscillating electric and magnetic fields creates what are known as electromagnetic fields. The electric and magnetic components of electromagnetic fields are intrinsically linked. When an electric field changes, it creates a corresponding change in the magnetic field, which in turn generates an electric field, and so on. This results in waves that are both electric and magnetic in nature, radiating out from the source.

In this way, electric and magnetic fields complement each other – one field can’t change without generating a change in the other. Their interaction allows electromagnetic waves to travel vast distances through mediums like air and vacuum. This is how many electromagnetic phenomena occur, from visible light to radio waves, x-rays, and more. Overall, the interdependence between electric and magnetic fields is fundamental to the existence of electromagnetic fields.

Natural Sources

The Earth and the atmosphere are abundant sources of natural electric and magnetic fields. Earth’s geodynamo, the motion of liquid iron in the outer core, generates a magnetic field that extends out into space and shields the planet from solar winds and cosmic radiation. The movement of charges within Earth’s atmosphere produces a natural voltage potential that can cause lightning strikes during thunderstorms. Currents of molten lava and changes in plate tectonics also induce electric and magnetic fields. Even the human body generates miniscule electric currents with every heartbeat and nerve impulse.

On a smaller scale, the weather can influence surrounding electric and magnetic fields. Friction from air and water molecules during storms produces static electricity capable of interfering with radio frequencies. Solar winds from space weather introduce charges into the ionosphere that can disrupt communications and power grids. The Schumann resonances, extremely low frequency electromagnetic waves in the cavity between the earth’s surface and the ionosphere, demonstrate a dynamic interplay between global lightning activity and the earth’s magnetic field.

Natural electric and magnetic fields have existed since the Earth’s beginnings. Life has evolved to thrive in the presence of these fields, though modern technology can amplify and alter the fields in new ways. By understanding natural fields, we gain perspective on the complex electromagnetic world we inhabit.

Man-Made Sources

Some of the most common man-made sources of electromagnetic fields include:

Power Lines

Power lines and electrical transmission systems produce strong electric and magnetic fields. The higher the voltage of power lines and the closer in proximity someone is, the higher the exposure to EMF.

Electrical Wiring

Home, workplace, and school electrical wiring all emit EMF at extremely low frequencies. The older the wiring is, the higher EMF exposure tends to be.

Wireless Technologies

Cell phones, cell towers, WiFi routers, smart meters, Bluetooth devices, and other wireless technologies emit varying levels radiofrequency electromagnetic radiation.

Everyday Applications

Electromagnetic fields are integral to many of the technologies we use in our everyday lives. Some key examples include:

Motors and Generators
Motors and generators make use of rotating magnetic fields to convert electrical energy into mechanical energy and vice versa. Motors are used in everything from small appliances to electric cars. Generators are used to produce electricity from mechanical power sources like wind, water, and engines.

Speakers and Headphones
Speakers and headphones contain electromagnets that vibrate in response to an alternating current, creating sound waves. This allows them to convert electrical signals representing sounds and music into audible sound.

MRI Machines

MRI (magnetic resonance imaging) machines use powerful superconducting electromagnets to produce strong magnetic fields that can detect changes in the alignment of hydrogen atoms within the body. This allows them to generate detailed images of internal body structures.

Wireless Charging
Wireless chargers use magnetic fields to transmit energy over short distances to charge batteries without the need for cables or direct electrical contacts. This electromagnetic induction allows convenient charging of devices like smartphones and smartwatches.

Potential Health Effects

Electromagnetic fields (EMFs) generated by power lines, electronics, and wireless devices have raised public concerns about potential health risks. However, decades of scientific research have not confirmed any definitive adverse health effects from typical everyday EMF exposure.

The major health effect that has been studied in relation to EMF exposure is cancer. High EMF exposure levels may cause biological effects like heating of tissues, but typical environmental exposure levels have not been conclusively linked to increased cancer risk.

Some epidemiological studies have suggested possible small increases in childhood leukemia risk with high EMF exposure, while other studies have not found evidence for such links. Overall the evidence is inconclusive. No causal EMF-cancer connection has been scientifically established.

A number of other health concerns like miscarriage, neurodegenerative diseases, cognitive impairments, immune system effects, etc have also been investigated. But research has not yielded sufficient evidence of harmful effects from typical environmental EMF levels.

While more studies are needed, the weight of scientific evidence does not confirm any significant public health risks from usual EMF exposure. Extremely high exposure levels may cause thermal heating and should be avoided, but everyday EMF exposure is considered safe according to most international health agencies.

Mitigating Exposure

While the evidence for negative health effects from electromagnetic fields is inconclusive, some people may still wish to limit their exposure as a precaution. Here are some tips for reducing exposure:

  • Increase distance from sources – Since electromagnetic field strength diminishes rapidly with distance, maintain distance from things like power lines, WiFi routers, cell phones, and other electronics.
  • Avoid direct contact with sources – Don’t lean against a washing machine or microwave while in use, and don’t sleep with cell phones or electric devices near your head.
  • Power down devices when not in use – Turn off WiFi routers, computers, TVs, and other electronics when you’re not using them.
  • Use wired internet connections and headsets – Use ethernet cables instead of WiFi, and wired headsets for cell phones.
  • Check your living and work spaces – Identify major sources of EMFs and make changes where possible by moving desks or rearranging living spaces.
  • Spend time away from sources – Spend time in low EMF areas like the outdoors or screen-free living spaces to balance exposure.

Making small changes to increase distance from and reduce time around sources of electromagnetic fields is a reasonable precaution for those concerned about exposure. However, as the science is still inconclusive on health risks, extreme measures to totally eliminate exposure are likely unnecessary.


In summary, electromagnetic fields are generated by both natural and man-made sources. The electric and magnetic components interact to produce fields that enable modern technology, yet may also pose health risks at certain exposure levels. Key takeaways include:

  • Electric fields arise from voltage and accumulate charge on surfaces.
  • Moving electric charges like currents generate magnetic fields according to right-hand rules.
  • Together, oscillating electric and magnetic fields create electromagnetic waves that enable communications, imaging, and more.
  • The Earth, solar storms, and lightning make natural EMFs.
  • Power lines, electrical wiring, and electronics produce artificial EMFs.
  • Understanding what creates EMFs allows us to harness benefits while minimizing potential harm. Additional protections may be warranted for vulnerable populations.

In conclusion, electromagnetic fields pervade our technologically advanced world. While further research on health impacts is needed, consumers can reduce exposures through prudent avoidance measures. Overall, recognizing the sources of EMFs is key to balancing their advantages and disadvantages in our lives.

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