How does electricity find the "Path of Least Resistance"?

FAQs and corrections: 1) Someone very correctly pointed out that my final question with the "cutting the line" test was ambiguous. For all of these tests I had the power supply set up as a current source, not a voltage source. If I had been holding a constant voltage at the start and end of the maze (also assuming I would have had thicker wires) the result would have been different =) 2) Multiple commenters have pointed out that the classic “hydraulic analogy” deals with water PRESSURE, not height. This means that we aren’t relying on gravity, so very small changes in pressure can have very large current flows and power transmission, but I think it’s less visual than height and I wanted a visual representation. Also, the pressure at the BOTTOM of the channel actually is higher when there’s more water above it, so it’s almost the same! 2b) I want to take this opportunity to mention the “surface charge” thing. Yes, real charge carriers in a wire spread out the excess charge (positive or negative) by placing excess electrons or depleting electrons, exclusively from the surface (but this only-at-the-surface thing only holds once the system is in steady state). The equivalent here with water is like imagining the water in the bottom of the channel is always present, that’s like the electrons in the bulk of the wire. The “wedge” of water you place on top of it is like the “surface charge”. It’s physically in a different place, and you aren’t actually changing the amount of water in the BOTTOM of the maze, but the wedge drives the slow of water all through the channel. I normally don’t even think about the surface charge because I visualize wires as 1D objects. 3) upon further inspection, I misread my meter when I was looking at the “tall step”. It didn’t read 5 mV, it read 0.5 mV. I think the circuit shorted out somewhere in the lower left just before I made these readings, which would explain why the 70-something number was too low and why the 0.5 number was WAY too low. 4) “The maze should start half full” - you’re right! In electricity, there is a significant driving force to move charge around if a wire has too many OR too few electrons. Wires like to be neutral, and where negative electrons can move, if they abandon the material they leave it with a net positive charge cause the (positive) atomic nuclei have nothing to cancel them out! In the water model you can think of this as actively pulling water from one end of the maze AND actively pushing water into the other end of the maze. But in water, you have to rely on it finding a steady state to flatten out because any stable water level can exist - in electricity it kinda already knows what it wants. 5) A lot of people have likened this to lightning, and lightning is way cool. Unfortunately I don’t claim to understand exactly how lightning “chooses a path”, but it’s more complicated than this. I know it tries many paths at once, but because it has to ionize channels of air do do so, it forms a filamentary structure instead of the more “continuum” flow/wave thing we see in a solid brick of metal. 6) Many commenters have said that I just have an RLC circuit bouncing around. The thin bits of foil behave like capacitors and store some electrons using electric fields, and the magnetic fields around the input wires are coupling to this and making it bounce. YES! This is exactly correct, you’ve just used the more technical wording. I was trying to keep it very linked to the water model so I said electrons were “sloshing”, but that’s exactly what happens in an electronic oscillator. It’s like one of those wave pools hitting resonance! 7) I’ve had a few comments ask what quantum physics has to do with this, and I would say for this experiment, nearly nothing. The reason electrons can flow in metals has a strong foundation in quantum, but it all ends up isotopic so it’s very possible to handle electron flow as a continuum thing. The problem with seeing quantum effects in wires is that electrons like to run into things, and every time they do, they kinda rerandomize. This means that to see quantum effects you need something REDICULOUSLY clean like an ultra pure GaAs/AlGaAs heterojunction with a 2DEG, or your circuit features need to be ridiculously small. A few years ago I had most of an experiment set up to fabricate a wire one atom thick but didn’t have time and tore it down. I’ll absolutely be setting that back up eventually. 8) Local forces - the water molecules can ONLY interact with (and sort of exchange information with) their adjacent molecules, but that’s plenty for them to solve a maze like this. Each individual water molecule doesn’t even know that it’s IN a maze, but the collective is able to solve it - I think that’s really beautiful. Electricity on the other hand, DOES have some longer range forces, and this was demonstrated very well by the Veritassium experiment I set up for real in the field. The thing is, all of these long-range forces can’t actually DELIVER electrons - nothing’s moving down a wire, which means that the results from these forces are always temporary, and if you want a DC current to flow, that’s still set up by relatively local forces between nearby electrons behaving like water. 9) a LOT of comments are recommending slomo guys. A 10million FPS camera would take a frame every 100ns. That would skip right over the larger sloshing/ripples that I said were way too slow. Electricity is mind-bogglingly fast!

They take all paths. The less resistance, the more current flows thru that path.

Never thought I'd see a voltage divider in maze form. Incredible.

Awesome experiment!

For me, as an engineer, watching this video is like relaxing in a forest near a lake in springtime. Thank you for this effort.

Using thermal imaging to trace the current is a really great idea. I taught Physics for 33 years before retiring 7 years ago, and I wish I had thought of this demonstration. I really did not see any errors in your explanation, good work.

Ever since I was in high school, I ALWAYS had an issue understanding how electricity flowed in series and parallel circuts (and combinations of such) with resistances. I never got a straight answer on whether or not current existed on the path with more resistance. This has helped solve that decade-long mystery for me. THANK YOU!

I'm currently a PhD student and about to publish a paper discussing spatial dependence of microscopic percolation conductance. We are studying the case of a conductive 2D lattice (essentially a maze), and although we use computer simulations to do thousands of runs (since we are interested in the average conductance) this video was still very illuminating. Thank you so much :)

Years back I majored in mechanical engineering and I still remember how much the fluid dynamics course blew my mind. When I learned how well everything in FD had a near perfect analog with electrical circuits it felt like things finally clicked in my head. Instead of living in a world with a near infinite amount of things all following their own principals and laws, most everything was more or less just different forms of the same fundamental objects and mostly seem to follow a relatively small and simple list of principals. It gives me hope that one day we may end up finding solutions to things like quantum gravity and the rules aren't as different as they look right now with our limited understanding.

It's very nice seeing so many Physics YouTubers duplicating experiments using different methods, but getting similar results. My understanding of these different concepts is increasing because of this. Well done. I especially like the 1 light second power transfer experiments by you and many others.

An idea for the water maze; block the entrance and exit and fill with clear water, then fill the ‘input’ with died water. Unblock the start and end and the stagnant zones should stay clear with the solution turning the died color. Great video!

This finally explains how electricity follows the path of least resistance. The backing up of the other routes forces the electrons to go the quickest, and least resistant route. I've had this question in my mind for a while and I finally have an answer. thank you

I am falling further and further down the rabbit hole of the scientific side of youtube and I am nothing but hyped for the journey. Thank you for having incredibly simplified yet also complex descriptions and explanations. It ensures my attention is held no matter what level of understanding I have at the moment. Amazing content. Thank you.

For the oscilloscope test, you should have used a capacitor instead of your power supply. You could show, side by side, the discharge curve of both the maze vs a simple resistor with equivalent resistance to the maze. Any deviation from the resistor curve would be the "electrons sloshing around the maze."

When I was in grade 6 I kept asking the teacher when we did our introduction to electricity unit "but how does the electricity know what's ahead of it, how does it decide where to go?" I like that you decided to cover this subject a lot, I have a better understanding now but you always make very informative and entertaining videos. I kind of thought I knew the answer when I started thinking of electricity like water and that made a lot more sense to me but I'm excited to see the video and see if I can get a more comrpehensive understanding.

I have a technical degree in electricity and took several circuits and electronics classes for a Computer Engineering degree. This one single video explained how electricity works and answered questions I've been trying wrap my head arouns for years. In 20 minutes. Bravo. Thank you so much, and I look forward to your future videos explaining electricity using water that you mentioned.

Nice demonstration! It always delights me when someone takes precious time to describe complex things in a simple way, thank you. The whole maze/path setup is a perfect example of sheet resistance, too.

This is why I have the notifications turned on for this channel from day one, I have been pontificating the particles/waves,, Thank you and keep up the great work, I can see this channel reaching 1M+ soon!

You never miss man. Always very interesting and thought provoking content.

I'm was an electrical engineer and I can safely say that your channel is the best explainer of how electricity behaves out there. Bravo, keep it up. I've binged your videos