After just taking an intense test in my Electromagnetic Theory class, I feel compelled to share some of the awesome things I’ve learned in this class. Electromagnetic Theory is so awesome that David Griffiths, the man who wrote our textbook on Electrodynamics, felt compelled to write an advertisement inside the book (hence, you read it AFTER you buy the book) as to why it’s worth studying. As he puts it, “It is scarcely an exaggeration to say that we live in an electromagnetic world—for virtually every force we experience in everyday life, with the exception of gravity, is electromagnetic in origin.” But it’s not just the forces we experience that makes E&M so relevant to our everyday life—E&M Theory has given rise to the majority of inventions that shape how we as humans live in the modern era.
If it wasn’t for E&M, we wouldn’t have light bulbs, television sets, cell phones, or Verizon FiOS. The entire field of optics is now attached to E&M, precisely because of how relevant a role the latter plays on the former (so you can thank E&M for your sexy contact lenses). Not only is Electromagnetic Theory rich in its depth and subtlety, but it also happens to be true that electromagnetic forces are the only ones to be completely understood. Yeah.
Have I convinced you of how awesome this stuff is yet? Well, let me take you back to the old days, when electricity and magnetism were considered separate phenomena. Most people associate electricity with unhappy things—getting zapped when you grab a doorknob, or getting struck by lightning—while people associate magnetism with fun activities, like sticking dirty jokes on your refrigerator (yeah, yeah, the refrigerator wasn’t invented yet…don’t get all high-and-mighty with me, punk). I jest…still, there didn’t seem to be a connection between the two, other than the fact that both had something to do with charges, moving or stationary. But Michael Faraday changed everything, when he discovered something called electromagnetic induction.
Yeah, I know…it’s a big word (two big words, actually). But here’s the idea: Let’s say you have a closed loop of wire in the presence of a magnetic field, supplied by, say, a magnet. If you wave this magnet back and forth (i.e. change the strength of the magnetic field), you will produce electric current in the wire! Let that sink in. This means that a changing magnetic field produces an electric field! Here’s a picture to help illustrate this:
This is the basic idea of induction, also known as Faraday’s Law. At first glance, this may not seem that important, but it blew my mind. This discovery later led to even more important ideas that solidified electromagnetism as one theory. But Faraday’s law has much more importance than you may think, because it is the reason we can live in the society we do. How so?
Faraday’s Law is what we use to power our generators! Almost everything we know is run by electricity. Our cities require huge amounts of electrical energy…have you ever wondered where it comes from? Con Edison runs huge electric generators, which use this principle to create electricity. They take giant magnets and spin them around, creating huge amounts of electric power, which is later shipped to your home via power lines!
Of course, it’s all much more complicated than I present it here, but this is the basic idea. Without Faraday’s Law and these generators, say goodbye to the life you enjoy living. Hopefully you can now appreciate some of the beauty of Electromagnetism. So make sure the next time you accidentally stick your finger into a socket, you remember the painful electrocution you receive is all thanks to the wonders of physics!