3 ms·

Why should we change how we teach about electricity, when we can change electricity to confirm to how we teach! :)

by 7bit 8mo ago

spaceywilly 8mo ago
Well, the water analogy actually holds up quite well if you consider the charge field moving, not the electrons themselves. This guy has a lot of great videos using water channels to explain electricity. It is fascinating how under a high speed scope, you can see the electrical Charge “flow” like water down each branch of a circuit. https://youtu.be/2AXv49dDQJw?si=5lPy_Mz4kJFdi80t https://youtu.be/2AXv49dDQJw?si=5lPy_Mz4kJFdi80t
- kazinator 8mo ago
  Even rubber dams stretched across pipes work exactly like capacitors. Firstly, they block DC: water cannot flow. But back and forth movement is conveyed (AC passes). Less capacitance in series, more in parallel. Two such dams in series do not have more capacitance because to get one to stretch, the other must stretch; they partially cancel. And since there are two, more pressure is needed to get the same stretch. (Same as more voltage needed to cram in the same charge: less capacitance). Inductance doesn't have an analog. To some extent, the inertia of the fluid cam model some of it, I suppose. Like what is "water hammer" in plumbing? The circuit is too suddenly broken, but the water wants to keep moving. There's gotta be a resulting momentary pressure rise there in the closed-off line, similar to voltage rising in an interrupted inductor. If the valve were some weak piece of crap relative to the mass of the water, the water would break it: like arcing.
  - aeonik 8mo ago
    Inductance is like a pipe with a flywheel inside it. the water pushes through the impeller/flywheel. the flywheel resists any changes to motion.
    - japanuspus 8mo ago
      Or just a long pipe where the inertia of the water resists change in motion. This is what causes the "water hammer" effect which is a problem for plumbers, but a great thing for all kinds of fun experiments, e.g. creating predictable cavitation [0]. [0]: https://www.researchgate.net/publication/321225042_A_novel_water_hammer_device_designed_to_produce_controlled_bubble_collapses https://www.researchgate.net/publication/321225042_A_novel_w...
      - kazinator 8mo ago
        Those who don't read grandparent comments are condemned to repeat them.
- Brian_K_White 8mo ago
  This was the stunning one to me. Just blew my mind literally observing it run up a dead end wire and slosh and rebound like water. Previously I was used to thinking of dead ends as simply functionally inert. That without a circuit, nothing at all happens in the dead end wire other than the potential for something to happen. Sure I know something more than nothing actually happens since there is an elevated charge there. But still just the mental model shorthand is that no circuit = no nuthin. But it's not. It's actually like a pipe with a little bit of air to allow for some compression, and even the dead end has a small flow that travels to the end and builds up against it, then rebounds back and eventially levels out at some homogenious but now higher pressure. That just boggles me! I love it.
disastronaut 8mo ago
The similarities are pretty strong as is. The method of images https://en.wikipedia.org/wiki/Method_of_images https://en.wikipedia.org/wiki/Method_of_images is used in both electrodynamics and aerodynamics because you can model sources and sinks for E fields and fluid flows using the exact same equations. Personally, EM didn't really click until I saw the vector calculus of EM applied to fluids.

Why should we change how we teach about electricity, when we can change electricity to confirm to how we teach! :)

by 7bit 8mo ago

Why should we change how we teach about electricity, when we can change electricity to confirm to how we teach! :)

Well, the water analogy actually holds up quite well if you consider the charge field moving, not the electrons themselves. This guy has a lot of great videos using water channels to explain electricity. It is fascinating how under a high speed scope, you can see the electrical Charge “flow” like water down each branch of a circuit. https://youtu.be/2AXv49dDQJw?si=5lPy_Mz4kJFdi80t https://youtu.be/2AXv49dDQJw?si=5lPy_Mz4kJFdi80t

kazinator 8mo ago
Even rubber dams stretched across pipes work exactly like capacitors. Firstly, they block DC: water cannot flow. But back and forth movement is conveyed (AC passes). Less capacitance in series, more in parallel. Two such dams in series do not have more capacitance because to get one to stretch, the other must stretch; they partially cancel. And since there are two, more pressure is needed to get the same stretch. (Same as more voltage needed to cram in the same charge: less capacitance). Inductance doesn't have an analog. To some extent, the inertia of the fluid cam model some of it, I suppose. Like what is "water hammer" in plumbing? The circuit is too suddenly broken, but the water wants to keep moving. There's gotta be a resulting momentary pressure rise there in the closed-off line, similar to voltage rising in an interrupted inductor. If the valve were some weak piece of crap relative to the mass of the water, the water would break it: like arcing.
- aeonik 8mo ago
  Inductance is like a pipe with a flywheel inside it. the water pushes through the impeller/flywheel. the flywheel resists any changes to motion.
  - japanuspus 8mo ago
    Or just a long pipe where the inertia of the water resists change in motion. This is what causes the "water hammer" effect which is a problem for plumbers, but a great thing for all kinds of fun experiments, e.g. creating predictable cavitation [0]. [0]: https://www.researchgate.net/publication/321225042_A_novel_water_hammer_device_designed_to_produce_controlled_bubble_collapses https://www.researchgate.net/publication/321225042_A_novel_w...
    - kazinator 8mo ago
      Those who don't read grandparent comments are condemned to repeat them.
Brian_K_White 8mo ago
This was the stunning one to me. Just blew my mind literally observing it run up a dead end wire and slosh and rebound like water. Previously I was used to thinking of dead ends as simply functionally inert. That without a circuit, nothing at all happens in the dead end wire other than the potential for something to happen. Sure I know something more than nothing actually happens since there is an elevated charge there. But still just the mental model shorthand is that no circuit = no nuthin. But it's not. It's actually like a pipe with a little bit of air to allow for some compression, and even the dead end has a small flow that travels to the end and builds up against it, then rebounds back and eventially levels out at some homogenious but now higher pressure. That just boggles me! I love it.

disastronaut 8mo ago

The similarities are pretty strong as is. The method of images https://en.wikipedia.org/wiki/Method_of_images https://en.wikipedia.org/wiki/Method_of_images is used in both electrodynamics and aerodynamics because you can model sources and sinks for E fields and fluid flows using the exact same equations. Personally, EM didn't really click until I saw the vector calculus of EM applied to fluids.