There has been a growing concern that because of the proliferation of electrical and electronic gadgets, humans have become more frequently exposed to electromagnetic fields (EMF) at dangerous levels. Reports of increased incidence of anxiety, headaches, decreased sexual appetite, nausea and fatigue have been suggested to have been caused by long-term EMF exposure in the home. These include such homely accoutrements as televisions, microwave ovens, cable, computers, radars, and mobile phones as well as power lines and nuclear power plants.
In general, the average person is exposed to constant doses of low-frequency, non-ionizing EMFs, and there is no evidence to suggest that this has an adverse cumulative effect on the health. The body itself runs on tiny bursts of electrical current resulting from biochemical reactions natural to normal bodily functions.
This is of course a lot lower than the electric current that runs through a construction site worker who accidently touches an exposed live wire, which can certainly pose a significant health threat. For the average person, however, constant low-frequency EMF exposure is generally safe, even when standing (without actual contact) beneath a high voltage power lines.
This bears special mention because there have been allegations that proximity to power lines increases the risk of developing childhood leukemia. Despite numerous studies into the matter (approximately 25,000 and counting), there has been no conclusive evidence that this is so, although it may be prudent to err on the side of caution and avoid prolonged exposure to these areas when possible.
This is not to say that EMFs have no effect on the human body. It induces currents to circulate and depending on how strong the magnetic field is can stimulate muscles and nerves and interfere with biological processes. Overall, however, the body is able to cope with EMF exposure provided it is at non-ionizing levels such as is found in normal everyday life.
An electromagnetic field or EMF is produced when a charged particle is accelerated or put in motion, typically with the introduction of an electrical current. Electrical fields can occur whether the charged particles are static or in motion, but a magnetic field is only produced when the charged particles are in motion, so to produce an EMF, there must be a current present.
As matter is made up of particles, it is possible to find an EMF anywhere in the environment. In fact, EMFs are constantly present all around us, but it is not visible. However, its effects can be observed, depending on two elements: frequency and wavelength.
Frequency is defined as the number of waves generated in a second while wavelength is the measurement from one wave to the next, which depends solely on the frequency. The more waves generated in a second or higher frequency the smaller the distance between waves or shorter wavelength. The different EMF forms are defined by a specific frequency and wavelength, which also determines if they are ionizing or non-ionizing EMFs.
EM waves produce energy. They are carried along by particles referred to as quanta (singular quantum), and high frequency EM waves generate more energy than low frequency waves. When an EMF generates enough energy, it can break the chemical bonds that hold molecules together, and these are called ionizing EMFs. Radioactive materials typically produce ionizing EMFs when they are accelerated, such as gamma rays and X-rays. This is why X-ray technicians don protective clothing, to prevent injury from operating X-ray machines.
EMFs occur naturally, primarily as a result of thunderstorms, which would account for the charged feeling in the air when lightning strikes. They are also generated from man-made objects such as electrical appliances and communication equipment. Lower frequency EMFs that are not strong enough to break bonds between molecules are non-ionizing EMFs, and these include radios, microwaves, and electrical household equipment.
There are numerous ways to solve problems in computational electromagnetics. While all are feasible, one method has seen a meteoric rise in popularity since its inception in 1966: the finite-difference time-domain method (FDTD).
FDTD is a method of solving problems in computational electromagnetics that uses Maxwell’s equations and derivations of them to illustrate the behavior of electromagnetic fields around an object. In these equations, space and time are combined into spacetime, rather than examined as two separate entities. This means that in a FDTD problem, for any given moment in time, there is only one possible arrangement of the electromagnetic fields surrounding an object.
The finite-difference time-domain method compares the change in an electronic field in time against a change in a magnetic field across space. Conversely, it also examines the changes in a magnetic field along an analogous electronic field in space. By incrementally stepping through individual moments in time while measuring the strengths of electromagnetic fields along the space, the FDTD method creates a model of the electromagnetic fields acting on an object.
The FDTD method is performed on a given space and equations are elegant enough to account for the properties of the materials being examined, such as their electrical conductivity, permittivity, and permeability. When put through a computer, the method essentially runs a simulation of the electromagnetic fields of an object. This creates a lot of data that can be mined and visualized. It’s even possible to simulate the effects of the addition of an electromagnetic pulse to the model, making the method invaluable to engineers working with antennae and other electromagnetic receivers.
While FDTD has gained a lot of popularity for its intuitiveness and ability to outline huge models as they change through time, it does have its drawbacks. FDTD requires a great deal of preparatory planning on the system. It calls for every aspect of the item upon which the simulation is to be run to be modeled at a degree precise enough to account for tiny differences in electromagnetic wavelengths. FDTD may also take more computing time than other methods, especially depending on the shape of the object being examined.
The Future Data Testing Department uses this method as well as others in its data acquisition, visualization, and machine learning projects. Of course, this is nowhere near a full discussion of the complexities of the finite-difference time-domain method, but we believe it’s a reasonable overview of how and why we employ it.
Computational electromagnetics, also known as electromagnetic modeling, is a fascinating study that helps scientists visualize the activity of electromagnetic waves on a given object. In computational electromagnetics, scientists use computers to solve, or at least approximate, solutions to Maxwell’s equations, mathematical formulas that describe the behavior of electric fields, magnetic fields, charges, and currents. They are a fundamental part of many areas of scientific study and advancement, including circuitry, and optics.
For computational electromagnetics, these equations are used to model the way an electromagnetic field will behave around an object. Prepared Maxwell’s equations are fed into supercomputers, though the systems are usually so complex that in most cases they aren’t completely solved, but rather approximated. This complexity arises from the number of iterations of complicated mathematical functions the computer has to perform in order to return a result. In order to get an accurate model, electromagnetic fields must be calculated for multiple instances in time, across numerous points, taking into account each possible interference or interaction. Because electricity and magnetism are linked, this is a daunting task, even for a supercomputer.
Computational electromagnetics is often used while designing communications technologies. For example, an engineer may be designing an antenna or other wireless receiver. These receivers function by detecting changes in electromagnetic waves, so it’s vital for the person designing them to be aware of how their devices interact with and create electromagnetic fields. Using computational electromagnetics practices, our friendly engineer can have an accurate visualization of the electromagnetic fields that would exist in his design.
Beginning to learn about electromagnetism can be a daunting prospect. While it is indeed complicated, electromagnetism is also one of the four known fundamental forces of physics, meaning there are limitless examples of electromagnetism in action.
Illustration of the directions in which magnetic field moves through a traditional magnet.
But what exactly is electromagnetism and where does it come from? Electromagnetism is the name given to the results of electric and magnetic forces acting on an object. Once thought to be completely separate forces, it has been discovered they actually share a close relationship with one another. For example, running an electric current through a metal wire creates a magnetic field around the wire. This field moves clockwise or counterclockwise around the wire, depending on the direction of the electric current, and emanates from it much like light or heat would. Likewise, one can create an electric current in a looped wire by moving it into an existing magnetic field.
Electromagnetism is responsible for countless interactions between atoms and their components. All matter is derived from the electromagnetic force between the atoms that make it up. Without this force, subatomic particles would fly around almost without rhyme or reason! This is because the electromagnetic force and other fundamental forces acting on subatomic particles work to hold them together. These particles typically have a charge, positive or negative, that attract them to or repel them from one another, just like play magnets have north and south poles. These charges and how they affect one another are understood through the rules of electromagnetism.
Another ubiquitous result of electromagnetism is electromagnetic radiation, more commonly known as light. All light, visible or not, is created by disturbances in electromagnetic fields. Differing rates in these disturbances lead to different kinds of light, with low-frequency disturbances creating radio waves, medium-level frequencies causing visible light, and high-frequency disturbances leading to dangerous gamma rays. These disturbances are called “photons” and are typically described as packets of light.
Electromagnetism is too complex a topic to be fully explained in a single blog post, but the Future Data Testing Department hopes that this has been a revelatory outline of some of its broad concepts.