Electrical engineering turns scientific discoveries into the devices and systems that power our world. This includes solar, wind, and other renewable energy sources as well as the electric transmission and distribution systems that deliver power to your home.
Electrons flow easily through materials whose atoms have loose electron shells, like the metals used in wires. That’s why we call some materials conductors. But other materials resist the flow of electrons.
Electromagnetic Radiation
Electromagnetic radiation (EMR) is a form of energy that carries electromagnetic waves. It is produced by electric charges and magnetic fields, such as those created by a current passing through a power line. EMR can affect the environment in several ways, including causing DNA damage and altering the behavior of plants and animals. It can also cause health effects in people, such as headaches and sleep problems. EMR can be found all over the world, including around homes and workplaces.
EM radiation has a wide range of wavelengths, from visible light to radio waves. Its properties depend on its frequency, with higher frequencies having shorter wavelengths. For example, microwaves have a much shorter wavelength than visible light. In terms of quantum mechanics, EM radiation is made up of photons, which are uncharged elementary particles with zero rest mass. Each photon has a specific amount of energy, which is proportional to its frequency, as defined by Planck’s constant.
People are exposed to EMR every day from a variety of sources, such as the 50/60 Hz power lines in homes and offices, cell phones, smart meters, wireless networks, and microwave ovens. While a few milliseconds of exposure to high-frequency EMF is not harmful, prolonged or daily exposure can increase the risk of disease and disrupt normal bodily functions. Moreover, EMF can damage DNA, which may lead to cancer and other diseases.
Electromagnetic Waves
All living organisms are bathed in a sea of electromagnetic waves. This is because all living tissues have magnetic properties. Electromagnetic waves are self-propagating: a change in the electric field causes the magnetic field to change, and so on. They are described mathematically by the two Maxwell equations (source-free) that link the changes in the electric and magnetic fields together and in phase. As such they can carry information, for example, radio frequencies can be used to transmit data.
Unlike sound waves which must bump molecules of matter into each other to travel through the medium, electromagnetic waves can pass through air, solid objects, and even vacuums. This makes them useful for a lot of technologies. Electromagnetic radiation (EMR) consists of crests and troughs called wavelengths which vary from a fraction of an atom to millions of kilometers. The shortest wavelengths scientists currently study are radio waves and microwaves.
The energy of an electromagnetic wave is proportional to its frequency, according to the Planck equation E = hf. Therefore higher frequency waves have more energy. They can also be polarized: they can pass through objects in one direction but not in the other. When a polarized electromagnetic wave interacts with matter it can be transformed into other forms of energy, such as heat or light.
Electromagnetic Fields
Electromagnetic fields, also known as electromagnetic pollution, affect different elements of the environment. They include electric and magnetic fields as well as radiation in the spectrum of radio frequencies, microwaves, infrared, visible light, gamma rays, and X-rays.
Anthropogenic EMFs operate at higher intensities for longer durations than do naturally occurring fields. Moreover, they often exhibit signaling characteristics (modulation, pulsing, etc.) that do not exist in nature and are amplified as a result of technology.
As a result, they pose an additional risk for species that do not evolve to cope with this novel environmental stressor. This is especially true for migratory birds, bats, and other vertebrates, as well as some fish and insects that use electromagnetic fields to navigate and hunt.
In the early 1800s, Hans Christian Orsted discovered that a current passing through iron filings could induce magnetic fields and Michael Faraday showed that time-varying magnetism can produce electricity. It was not until the late 1840s that these two aspects of the electromagnetic field were recognized as part of a larger phenomenon called electromagnetic radiation.
While there is a growing body of scientific evidence that anthropogenic EMFs can cause adverse health effects, there remains no clear causal link between these exposures and the conditions reported. Nevertheless, there are many factors that can be taken to reduce one’s personal exposure. These measures include increasing the distance between an individual and a source of EMF, using power strips to deactivate appliances, and limiting the amount of time spent near a source.
Electromagnetic Potential
Every time you tune a radio, watch TV, send a text message, or microwave popcorn, you are using electromagnetic energy. Electromagnetic energy comes in many forms, from very long radio waves to very short gamma rays. It can travel through any material, including your body.
The speed at which electromagnetic energy travels through a medium depends on its density. If a wave enters a different medium with a higher density than the original one, its speed will increase. This is the principle behind refraction: if you hold a pencil up to a glass of water, for example, you will see the tip of the pencil bend toward the inside of the glass because the density changes at the interface between the two substances.
Another way that electromagnetic energy can affect the environment is through a magnetic field. The magnetic vector potential is a very important concept in modern physics and represents a single entity that describes the electromagnetic force. It is one of four fundamental forces recognized in modern physics (along with the strong nuclear force and the weak nuclear force).
In addition, electromagnetic energy can interact with matter to change its properties. This is the case with microwave radiation, which can cause water molecules to vibrate faster and heat up. It can also cause the particles in an atom to move, or even change their energy level, by emitting gamma rays.