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A Slice of the Electromagnetic Pie This month’s subject is electricity and its progeny electromagnetism. These are at the heart of IT. There are four great forces of the universe. They include the Strong, Weak, Electromagnetic, and Gravitational forces. The “Strong” and “Weak” forces deal with nuclear bonds and are rarely experienced in our lives. Gravity is something that we experience daily. Humanity continues to drop things and, on occasion, fall. It is the Electromagnetic Force [“EM”] that has become the unseen hero of IT. We are awash in EM waves. They are produced by natural phenomenon but grow ever more prevalent as humanity’s scientific prowess develops. These infinitely propagating waves are the result an electron being accelerated by an electrical field (“accelerated” includes changing direction as in a curved wire). The magic arises when a moving electric field produces a magnetic field, and that magnetic field then produces a new electric field. This process selfpropagates with each producing the other ad infinitum. These two forces come together like two lovers practicing a quadrille dance to infinity. These continuously oscillating electric and magnetic fields together form a bundle of energy that we label a “photon.” While most folks think of photons as something visible, we are “blind” to almost all frequencies. Most animals have a higher visual acuity than humans. As stated in The Body by Bill Bryson, “Because we were once nocturnal, our ancestors gave up some color acuity—that is, sacrificed cones for rods—to gain better night vision. Much later, primates re-evolved the ability to see reds and oranges, the better to identify ripe fruit, but we still have just three kinds of color receptors compared with four for birds, fish, and reptiles." While color may not be our strong suit, our rod cells are powerful enough to detect a single photon. That said, we need at least nine photons received within 100 milliseconds to alert the brain. Given the ongoing variety of electromagnetic waves being processed, it is not surprising that about a third of our entire cerebral cortex is engaged with vision. get IT done
We can only see a sliver of the vast electromagnetic spectrum, perceiving frequencies in the narrow spectrum of 430 to 770 terahertz. We cannot see lower frequencies [radio waves, microwave, and infrared] or higher frequencies [ultraviolet, X rays and gamma rays]. We have been experimenting with electricity for ages, but it was only in the last 150 years that we understood the relation between electricity and magnetism. In 1865 James Clerk Maxwell proposed the “Theory of Electromagnetism” which showed that light was electromagnetic radiation. Maxwell not only postulated the existence of the EM spectrum, but he also developed experiments that demonstrated electromagnetic induction. This concept remains central to generators and, when reversed, electric motors. Electricity came of age at the Worlds Fair in 1893. This event introduced electric lighting to the public at large, bathing the fairgrounds in an awesome “magical glow.” As noted in the book AC / DC by Tom McNichol, “the children’s author L Frank Baum was so enthralled by the site that he used it as inspiration for the Emerald City in his Wizard of Oz book series.” While light has provided us succor throughout history, it is the unseen part of the spectrum that I would like to probe in the next few articles. Those unseen waves dramatically impact our lives. Not only do we use the power of electromagnetic waves in medicine, cooking, and communication but it is at the heart of all things “IT.” Next month, we will discuss how the EM spectrum truly undergirds our civilization. See the light and Think About IT!
Tony Keefe, COO, Entre Computer Services www.entrecs.com AUGUST 2022 The ROCHESTER ENGINEER | 13
