Why does WATER change the speed of electricity?

The electrons are back! This is the first of three videos discussing electricity - what is it, how does it work, how do we use it? This first installment talks about the speed of electricity and electrical signals in wires. Next up is Ohm's law, and what resistance really does in circuits, and third, I'll be taking another look at the experiment featured on Veritasium last year, building on the first two videos to explore the mechanism that couples the two long wires with a little more scrutiny. Enjoy!

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Music in this video:

[AlphaPhoenixChannel]

Corrections and FAQ answers:
2) Pre-emptive clarification about the overly-philosophical ending: Sine waves are not the only orthogonal basis set that can be used to construct any function, so you could argue that any similar construction is arbitrary and math-only, and would STILL be indistinguishable from reality. That said, sine waves are really pretty (and can actually be used to solve equations that demonstrate propagation).
3) Microwaves! I've had a bunch of people ask about the "resonant frequency" of the water molecules (or any dielectric). This is exactly how your microwave works, and at this frequency (2.4 GHz I believe), the energy transfer from the field to the water molecule is most efficient.
4) What's the difference between this and coax, and velocity factor? In coax, the entire field is contained between the core and sheath, so the cable designer has COMPLETE control over the speed of propagation in the cable by choosing the dielectric insulation that the field has to pass through. This experiment I've set up is REALLY terrible at making sure the field has to interact with the water. There's probably a lot of "field leakage" I'm not dealing with. coax is amazing in it's ability to be controlled and uniform.
5) The frequency of flipping a switch: in the absolute most hand-wavey way possible if we assume that the ~40 nanosecond rise time for the signal (switch flip) is actually 1/4 of a sine wave (as in cut out of a wave, i said hand-wavey), then the relevant frequency would be ~6 MHz. In reality this is probably within an order-of-magnitude, but many additional frequencies are needed to reconstruct the exact shape of that rise, and I don't have a great intuition for which ones carry the most energy.
6) I did perform a "zero length" measurement to confirm that the scope channels were synchronized and the "send" and "receive" signals rise at the same time. I don't remember the offsets I measured right now, but they were much smaller than other errors in the system, like measuring the length of the wire!
7) I didn't realize at first that the pipe was at a bit of a slant, so the end the camera was looking at was only part full when the wire at the other end was already submerged. I don't even want to think about the weird physics problem of having water ADJACENT to a wire and trying to predict anything, so I only talked about the "empty" and "full" configurations.
8) ???

[Martmists]

Have you considered making a video on how oscilloscopes work? While the core concept may be simple, any software developer knows it's ridiculous to measure something smaller than a nanosecond, let alone record events for _longer_ periods of time and filtering it to .1 of a nanosecond.

[nepdisc]

For so much of my life I've just seen electricity as inexplicable magic that only people who dedicate years and years of studying to it can ever come close to understanding, but these videos are so elucidating that I actually feel like I'm finally starting to grasp the concept and that's HUGE. Thanks for doing all of this, it's fascinating to see.

[skylerlehmkuhl]

While watching the bit about how the different frequency components would "smear" the signal, I found myself wondering if the same would happen with visible light - and then realized that's exactly how a prism turns white light into rainbows.

[Geopholus]

You are one of the very very few people who do technical videos on electronics/physics, who actually have an excellent understanding of electronics, and manage to describe it simply and accurately!

[radar_x]

The equation for propagation delay you showed only applies to EM waves is an isotropic media - like free space or within a single dielectric. Whereas the wire in the tube of water has water surrounding the outside of the wire thus impacting the external EM field but there are E-fields still within the wire (not even accounting for frequency-dependent skin depth effects) and these are still propagating near speed 'c' which is why the overall speed of signal propagation only slightly decreased by the submerged wire. Excellent video by the way. BTW, this comment is from an RF engineer.

[Wisterson]

As a licensed electrician. This is they type of content that keeps me safe and educated. So thankful for your hard work and enthusiasm.

[LostFromLight]

I really enjoy thinking "with" you. Thanks for the slightly personal yet really scientific way of directing your videos. You're really able to let me immerse in the experiment with you.
Can't wait for the next episode!

[randomelectronicsanddispla]

The difference in speed is actually quite significant when you start tunning oscillating circuits and antennae. Transmission lines have up to 50% in speed difference

It might be worth doing the same test with a piece of coax cable.

[scarletevans]

I watched Veritasium vs Electroboom's back and forth videos debate about this matter and, in my opinion, I have to say that you explained how the electricity works even simpler and better than them!
Thank you for this video! ♥

[dking]

This is another great video from your channel! One suggestion that I'd like your opinion on is that at 10:36 you showed an electron with its field lines moving out from the electron at the speed of light, I think an interesting alternative way to illustrate/animate this would be to show the electron at rest with the field lines already present and when the electron moves this creates a "kink/curve" in the field lines and the "kink/curves" themselves propagate at C. I'm sue animating these videos in difficult and time consuming beyond my comprehension but I was just wondering if my mental picture made sense to you. Thanks for the great content!

[dennyoconnor]

As a Ham Radio guy I find your tests fun - and confirm what I have found in 60 years of playing with antennas. Your wire with thick insulation will have a Velocity Factor decrease of roughly 1% compared to a bare wire. I (we hams) see this in building antennas that are resonant at a specific frequency and using different wire insulation types. Wire thickness does have more effect on Q (which affects the bandwidth of resonance) than on Velocity Factor, but it is not in-your-face apparent. And your wire in a pipe demonstrates that the velocity factor of a coaxial feedline is highly dependent on the insulation and will generally have a velocity factor of 65% to 85%. Cheers, eh wot. DOC - K8DO

[VisualElectric_]

This is a very interesting experiment. I recently did a video on the first frequency dependent transmission line models developed to explain behaviour of first the transatlantic telegraph cable in the 19th century - it took several minutes to send a few messages because the line was surrounded by water, giving a huge capacitance. The background theory is fascinating.

[dougcox]

Not a quibble, just a tip. Your scope was mistriggering a lot and it took me a minute to see why. You had the trigger level way near the top of the signal. Just move it down to somewhere in the middle where it's less noisy and very distinct. Take advantage of that sharp rise time.

[tomaszbekas]

I came here after watching your current most recent video "An intuitive approach for understanding electricity" and I see that at 23:55 you have a shot from an experiment done in that video. It shows how much time & effort it takes for you to create videos and how much you focus on a quality. I appreciate it very much, kudos to you.

[maxheadrom]

A professor of mine in college did a simple cool demonstrations using a book, PVC tubing, a candle and some matches. You'll need two people for this, btw.

Get the PVC tube (2 inches, 1 inch ...) on a desk. Light the candle and put the flame at near one end of the tube - get one of the 2 people to stand very close to the candle. The other person then gets the book, opens it and near the other end of the tube and then slams it closed. The book will make wind and the candle will go off ... but will the candle go off because of the wind????

[cdmnky]

It's been almost a yr since the Veritasium video and we're still squeezing great content out of the "controversy", I love it

[eikeschwarzwald]

This is such a wonderful series. I'm so glad, that the "flame war" produced something with such a scientific precision :D This is not just the V-style clickbait stuff <3

[gingermany]

So many good analogies to light here (which makes perfect sense really). Adding a pinhole to a light path doesn’t slow down the light anymore than increasing the resistance of a wire slows down a signal.

[danlscan]

You've managed to explain to me why some phenomena happen only with AC or DC and why some properties of AC are frequency dependent. Very good stuff for a technician to tuck away and digest. Thanks!