I am very sure most of you have seen this by now, but it’s such an interesting topic I wanted to start a thread on it, as the public discussion this video has generated is amazing, and there is a lot to be learned here.
on the 19th November, 2021, Veritasium (Derek Muller) posted a video to YouTube titled “The Big Misconception About Electricity” (https://www.youtube.com/watch?v=bHIhgxav9LY), which, in a nutshell discusses the EM fields that are generated in circuits, and that those EM fields travel at the speed of light which can have unexpected consequences. In the video it is shown that a light bulb will be powered by the EM wave before the electrons can reach the bulb.
Whilst what Veritasium says is completely true, I feel that he glosses over many points, and makes a general statement which, without sufficient qualification, is not actually correct - and it is this that has generated the discussion.
To be honest, when I first watched it, I left feeling confused… that I had missed something, or that my understanding of electrical engineering was incorrect. I have since gone back to my text books, to refresh and double check my understanding, some things I hadn’t thought about since college! I can certainly see that for beginners in EE this video could easily create a great deal of confusion, and this is the point of this thread.
The video can easily lead into deeper studies (and checking your understanding of)
- Electron flow in both AC and DC circuits
- DC transients vs DC steady state (this is one point I think the video greatly misses)
- Transmission lines
- Electromagnetics and Electrodynamics
- Maxwell’s equations & Poynting vectors
- EM radiation (which leads to EMI in practical engineering)
One take away I had (and Dave Jone’s response seconded this) - there is a point where practical engineering gives way to theoretical physics, and you need to know where to draw the line. Certainly having a deeper understanding can help, but simplified models when applied correctly are still enormously valuable - for many, many situations, for all intents and purposes it’s fine to think of electrons flowing in the wires as we do with the water-analogy.
There will always be the possibility to dig deeper, and there is much we still don’t understand, but it doesn’t stop us designing real-world, practical circuits that achieve our purpose and we need to be careful we don’t go deeper than is necessary and allow it to block progress. Sometimes you don’t need to fully understand something to make use of it, it can be ok to accept some “magic” from time to time! For example, we don’t really need to know about quarks to understand how to turn an LED on from a GPIO pin - and my mother (a maths teacher) has to constantly remind me of this, in school I would find myself constantly diving deeper and deeper into why things are, and that often prevented making practical progress. Remember what your goal is!
with that said, here are some responses to the original video that I enjoyed (or didn’t!)
EEVBlog Response: https://www.youtube.com/watch?v=VQsoG45Y_00
Robert Feranec: https://www.youtube.com/watch?v=Lp_b8gQpxW8
RSD Academy (#1): https://www.youtube.com/watch?v=--v5BXmFYv4
RSD Academy (#2): https://www.youtube.com/watch?v=WRR0gHh9a4s
(personally I found the RSD Academy #1 video to be rather poor, however his second version is much better!)
I would be fascinated to hear what others in our community here think, there are many very experienced engineers in our midst, as one example having followed @scott.xentronics recent webinars on EMI I imagine he would have some thoughts!
(As I write this, the video is trending at #31 on YouTube which is amazing for a science/engineering video and it has started a massive public discussion, which again, is a good thing. Probably the fact that it is not, in my opinion, a great explanation has generated the discussion, which in turn makes it trend, which in turn gets more people involved in the learning process - so, making a poor video, might have been a good thing this time?!)