A comments on Veritasiums How electricity actually works

Derek over at Veritasium made a video on electricity that apparently spun allot of opinion, so he had to make an explanation and an extra video to explain and prove his original claims. Nice video and funny that it got so much attention. Of course, as a microwave engineer, thinking about fields all day, I was not very surprised about the claim.

However, I think he did make a mistake in the follow up video. Or at least again was intentionally vague :). In the video he seem to indicate the the waves on the transmission line is excited by capacitive coupling between the lines. I think this is wrong. The excitation to the transmission line is actually inductive. I have not done the math, but I would be very surprised if it is capacitive. There is really no charge variation when the switch is turned on. However, there is current, and thus it is the mutual inductance that excites the wave.

He also made another mistake in his model of the transmission line. In the circuit with the transmission lines, they are on each side of the source/load. However, that is not the correct model. The transmission lines are actually connected to a (very complicated) source in parallel, and then shorted in the far end where the wave is reflected back. I think this is a resonably accurate model of the system (ignore the actual values, which I did not bother to change):