Electromagnetic Field

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EMF Electromagnetic Field

An electromagnetic field is referred to as a physical field of objects that are charged electrically. It is one among the available four fundamental forces of nature, and others include weak interaction, gravitation, and intense interaction.

The electromagnetic field affects the behavioral change of charged objects surrounding a specific place. It extends throughout the space indefinitely and is called electromagnetic interactions.

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It is an electric and magnetic field combination and is often considered as the electromagnetic field sources. The electric field is generated by the stationary charges, while the moving charges produce the magnetic field. Here we can find out the difference between the electric and magnetic fields.

Maxwell's Equation and the Lorentz Force Law explains how the interaction between currents and charges happens with the electromagnetic field.

What is Electromagnetism?

The term electromagnetism is the branch of physics that deals with the electromagnetic force, which occurs between the electrically charged particles.

Structure of the Electromagnetic Field

The structure of the electromagnetic field can be classified into two distinct methods. They are Continuous Structure and Discrete Structure.

  • Continuous Structure

The electric and magnetic fields classically are thought of as being produced by the smooth motions of charged objects. For example, oscillating charges produce variations in magnetic and electric fields that may be viewed in a continuous, 'smooth', and wavelike fashion. In this case, the energy is observed as being transferred continuously through the electromagnetic field between any two locations. For example, the metal atoms in a radio transmitter appear to transfer the energy continuously. This view is useful to a particular extent (radiation of a low-frequency), but the problems are found at higher frequencies.

  • Discrete Structure

The electromagnetic field can be thought of in a more 'coarse' way. Several experiments revealed that in some circumstances, electromagnetic energy transfer is described better as being carried in the form of packets known as quanta (in this case, photons) with a fixed or standard frequency. Planck's relation binds the photon energy (E) of a photon to its corresponding frequency (f) through the equation given below. 

E=hv

Where, 

E is the Photon Energy

h is the Planck's Constant, and 

v is the Frequency of Photon.

Sources of Electromagnetic Fields

The electromagnetic field sources can be given as listed below.

  • Natural Sources

The electromagnetic field can be seen everywhere in the surroundings, but are invisible to the human eye. The electric fields are formed by the electric charges present in the thunderstorms environment. While the magnetic field of the earth causes the compass needle in the North-South Direction, this is used as a navigation for birds and fishes.

  • Man-Made Sources

Besides the natural sources, the electromagnetic field also includes the energy which is generated by the man-made sources. A few of the human-made electromagnetic field sources are electricity passing through the power socket, x-rays, and many more. It depends on the frequency of radio waves and how they are associated. For example, the high-frequency waves are used to broadcast information through television antennas, mobile networks, and radio stations.

Health and Safety of Electromagnetic Field

The potential effects of the electromagnetic fields on human health widely vary based on the intensity and frequency of the fields.

The potential health effects of the very low-frequency EMFs surrounding the electrical devices and power lines are the subject of a significant amount of public debate. It is on-going research. The United States National Institute for Occupational Safety and Health (NIOSH) and a few other US government agencies do not consider EMFs as a proven health hazard. NIOSH has also issued some precautionary advisories but stresses that the data is currently too limited to draw useful conclusions.

Employees working at electrical equipment and its installations can be assumed to be exposed to high electromagnetic fields. Computers, monitors generate it, and more is negligible owing to the low field strengths. However, industrial installations for welding equipment or induction hardening and melting may produce considerably higher field strengths and need further examination if the exposure cannot be determined upon the manufacturer's information, comparisons with analytical calculations, or similar systems, measurements that are to be accomplished. The evaluation results help to assess possible hazards to the worker's health and safety and to define protective measures. Since electromagnetic fields may influence either passive or active implants of workers, it is vital to consider the workplace exposure separately in the risk assessment.

Besides, radiation from other parts of the electromagnetic spectrum, like ultraviolet light and gamma rays are known to cause significant harm in a few circumstances.

Differences Between the Electric Fields and Magnetic Fields

Electric Fields

Magnetic Fields

Electric fields arise from voltage

Magnetic fields arise from current flows

Strength is measured in V/m (Volts per metre)

Strength is measured in A/m (Amperes per meter). EMF investigators use a relevant measure, flux density (millitesla (mT) or in microtesla (µT))

Strength of the field decreases with the source distance

Magnetic fields exist sooner as the device turns on and current flows

Greatest building materials shield the electric fields to an extent

Field strength decreases with the source distance

FAQ (Frequently Asked Questions)

1. Mention Some Sources of Electromagnetic Fields in Everyday Life.

Electromagnetic fields exist anywhere in all the environments, including our workplace, home, and school. Natural or human-made sources generate these fields.

A few of the natural sources of magnetic and electric fields are listed below.

  • Lightning - lightning generates electromagnetic force

  • The Earth's Magnetic Field - it makes a north compass point

  • Visible Light - we can be able to see using optical radiation

A Few of the Human- made sources of electromagnetic fields are listed below.

Electrical Appliances

  • Hair-dryers

  • Vacuum cleaners

  • Refrigerators

Radio Communications Devices

  • Television and AM / FM radio

  • Emergency service radio (police, ambulance, fire)

  • Cordless phones

  • Air traffic control

  • Mobile phones

  • Remote controls

  • Wi-Fi modems

2. Mention the difference between Non-Ionizing Electromagnetic Fields and the Ionising Radiation.

Electromagnetic Fields: The quanta particles carry electromagnetic waves. Higher frequency (shorter wavelength) quanta waves carry more energy than lower frequency (longer wavelength) fields. A few electromagnetic waves carry much energy per quantum that they have the ability to break bonds between the molecules.


In the electromagnetic spectrum, gamma rays are given off by the radioactive materials. Cosmic and X-rays carry this property and are called 'ionizing radiation'. Fields with insufficient quanta to break molecular bonds are known as 'non-ionizing radiation'. The electromagnetic field sources which are of the man-made form a significant part of industrialized life, electricity, radiofrequency fields, and microwaves are found at the relatively long wavelength, as well as low-frequency electromagnetic spectrum end. They are unable to break the chemical bonds of their quanta.