4 ms·
“Few”, yes. But definitely some. I don’t think you can have propagation of EM wave through a conduit without at least pushing one electron into the conduit and
by reaperman 2y ago
“Few”, yes. But definitely some. I don’t think you can have propagation of EM wave through a conduit without at least pushing one electron into the conduit and removing one electron from the other side of the conduit.
- dekhn 2y agoYes, but it's subtle; see https://en.wikipedia.org/wiki/Drift_current https://en.wikipedia.org/wiki/Drift_current and https://en.wikipedia.org/wiki/Drift_velocity https://en.wikipedia.org/wiki/Drift_velocity and https://en.wikipedia.org/wiki/Electron_mobility https://en.wikipedia.org/wiki/Electron_mobility for more details I was pretty surprised about this since I had mistakenly believed that electrons had a velocity near the speed of light, which I think is only true in particle accelerators.
- reaperman 2y agoIndeed - I thought most college Physics 2 courses teach that electrons actually move quite slowly through conductors. It’s the “wave” which propagates near the speed of light, not the particles.
- dekhn 2y agoMy mistake was being a biologist, and skipping or sleeping my way through the EE part of physics :) and then saying the wrong thing in front of some very smart people
- reaperman 2y agoLord, I make that mistake on HN nearly every month. At least you didn’t have a “Putnam award” moment: https://news.ycombinator.com/item?id=35079 https://news.ycombinator.com/item?id=35079
- dekhn 2y agoI've had something similar- when I was deciding what grad school to go to, I was explaining how RNA enzymes work to some professor at UC Boulder, who ended up being Tom Cech (who won the Nobel for discovering RNA enzymes); he had to correct a lot of the details I messed up. I ended up going to UCSF and fortunately didn't try to explain prions to Stanley Prusiner. In short, nearly everything I have learned is from saying dumb things in front of very smart people who instantly understood my misunderstanding and knew exactly how to explain it so I understood. That includes Sanjay Ghemawat and Jeff Dean telling me "your idea isn't so good, it's n-squared, here's a linear solution"
- reaperman 2y agohttps://youtu.be/2Vrhk5OjBP8?si=gDXZKYeFkVoAs_LG https://youtu.be/2Vrhk5OjBP8?si=gDXZKYeFkVoAs_LG AlphaPhoenix did an amazing experiment to measure the speed of electricity FWIW. His other videos are incredible as well and explain EM physics in an absolutely outstanding way.