Electricity and Magnetism, Part 1

I’ve long wanted to take a course about electricity since it’s one of the most mysterious parts of physics to me despite it being essential to everyday life. There doesn’t seem to be anything available on it on Coursera. I’ve been aware of the competing edX platform for a while now but hadn’t taken the time to explore it. So when I saw that it does indeed have a course on this topic, I immediately made an account.

This one is taught by Jason Hafner of Rice University and consists of five weeks worth of material. Being part one of a two part course, the coverage only stretches from the concept of charge to circuits, so don’t expect to be fiddling with complex electronics here. I consider the course to be quite difficult, especially because of the mathematics involved. There is plenty of calculus in the later weeks. Due to this, I could only follow along so far and eventually just settled on watching the lecture videos as I had no hope of completing the weekly exercises, let alone the final exam.

From the portions that I could understand, the content is nothing short of top notch. I loved how everything flows from the very simple principle that everyone knows: that charges of the same sign repel one another and opposite charges attract. It’s easy enough to understand this as well as do the math of the forces that are generated when there are only two point charges but things get complicated surprisingly quickly when there are many point charges involved, all of whom exert a force on each other. It’s when the lectures move from point charges to lines of charge, planes of charge and spheres of charge that the math go over my head but I still really dug how everything still falls out of those basic principles.

Hafner is a fantastic lecturer. It’s a given that he knows how to present material but I especially appreciated how he takes the effort to liven things up every once in a while. Hafner performs all kinds of experiments right on camera and is YouTube-savvy enough to pick the most spectacular ones. He notes that students love to see the professor get hurt, or at least be at risk of getting hurt, so he duly delivers the goods by shocking himself. At one point, he even disassembles a capacitor to show what it’s made of, a great reminder that the subject concerns real objects and not just math on the board. The questions from students that he addresses are well chosen as they’re exactly the kind of obvious but dumb questions I’d have thought of.

I learned plenty to satisfy myself and even had some of the questions I’ve always had about electricity answered. For example, I’ve always known that in a conducting material, it is only ever the negatively charged electrons that move but why do people often talk about the positive charge moving? As Hafner explains, this is a kind of abstraction as we can kind of think of the holes left behind by the electrons that have moved being a sort of positively charged pseudo-particle. I really liked how Hafner reminds us that we should always be aware of when we are using a model and the limits of that model so that we don’t think of it as literally real.

This is the first time I’ve ever taken a course on the edX and Hafner even throws in a dig about how Coursera is to the PC what edX is to Macs. Even though I’m a life-long PC user, I have to say that the technology on the edX platform seems marginally superior. In particular, it has the ability to embed three-dimensional graphics on pages that you can freely manipulate, allowing students to more easily visualize objects and models in a 3D space. Their system also appears to allow more varied types of questions for the quizzes. All of their lecture videos actually hosted on YouTube so it’s actually possible to view them there and of course there’s no worry of video hosting problems like this.

Needless to say I was tremendously impressed by this course and regret only that I lack the mathematical background to take full advantage of it. I already know that the next online course I’m taking will be AP Physics 1 on the same platform which lists professor Hafner as one of the instructors.

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