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Comment by Waterluvian | Hacker News Reader

I can infer what the "hydraulic analogy" is, but I can't say it has ever been present in my life. It certainly was never touched in high school electrical engineering. Anyone have differing experiences?

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I've heard things such as "voltage is like water pressure (psi), resistance is like the size of the pipe (cross-sectional area), current is like the flow rate (gpm)" and so forth.

given how it dismissed that model, it seems odd that this article then immediately starts talking about the ‘electron gas’ and throws around an analogy of voltage to a pressure difference in the gas.

Apparently the pneumatic model is preferred over the hydraulic one.

Personally I think the problem with the ‘hydraulic model’ is that people visualize it with wires as fluid filling pipes, with pressure as the driving force. I think you get a lot further if you imagine your circuits as water running in open channels with a free surface. The water needs to be able to slosh.

This took a lot of effort to dig up (answers your questions on "thinking hydrolicaly") - so you must watch it /g

https://www.youtube.com/watch?v=OEzuZ6BpC-g

p.s. just that comment in passing starting at 12:10 is absolute gold: he casually drops the equivalence to state and function in basic electrical components. HN, this is one of the most wonderful - you will learn a lot - lectures delivered in exceptionally modest, accessible, and friendly manner.

Both in high school and college, my instructors used it. I found it useful and it remains the default go-to mental model for me. Wikipedia even has an article on it: https://en.wikipedia.org/wiki/Hydraulic_analogy

When I was a kid, my father tried to explain "how electricity works" using water analogies.

Works well enough to make a curious kid stop asking questions, but won't take you much further than that.

I guess it depends how far you want to go, but the water analogy seems pretty useful to me. It encompasses V, I, R, capacitors, resistors, and inductors.

I think it's a recent thing. I first heard about this analogy some time in the 2010s.

Voltage has been called "pressure" for a very long time, although I'm not sure if it's strictly a hydraulic analogy.

Yep. Traditionally, voltage was the "tension" applied to the system. Pulling rather than pushing there, but same idea. Still occasionally seen in "high tension lines" etc., and for some reason (worked on too many tube amps over the years?) I sometimes still write HT/LT instead of HV/LV.

Where else would you get "voltage sink", "gate" (similarly German "Gatter" - gate, flip flop, switch).

Pretty sure Maxwell used it.

The analogy is just to try to convey the concept of a field and the associated vector calculus. An analogy isn't necessary for Newtonian mechanics and scalar calculus because humans intuitively understand thrown balls etc.

Maxwell's fluids followed EM field lines, not current flow.

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