'An intuitive approach for understanding electricity' AFTERSHOW

Welcome to the "aftershow" video for "An intuitive approach for understanding electricity" and the water channel model! I'm trying out this format because there are frequently corrections I need to make and really good questions I'd like to be able to answer, but if half of the videos on the channels were like this, it'd be kinda weird. so welcome to the second channel!

Today I'm making one correction about holes and ions, relaying a fantastic analogy from a viewer, discussing how to add capacitors, inductors, transformers, and series/parallel batteries to the water channel model, and answering a great question about energy transfer between electrons and the lattice in a wire. Hope you enjoy!

Media Credits:
Pink Lemonade by Silent Partner is licensed under a Creative Commons license

0:00 intro
0:47 Positive charge carriers
5:12 A cup of water in the ocean
6:28 Capacitors
8:55 Inductors
13:16 Transformers
15:27 Batteries in series and parallel
22:41 Temperature of electrons
25:59 outro

[sondreandersen]

I think the informal and "low-budget" format is great! It gives some leeway to throw a few different views and drawings on the screen, making it more likely one will resonate.
I would reccommend softening/changing the music playing during the drawing, though. I found it too loud/energetic, and quite jarring both when it starts and when it stops.

[ReRoy]

Loving this format! Best way I know of to begin a 'deep dive' defining succinct jump-off points to discuss. Personally, I find a discussion of simple machines and how they relate to EM properties and components is interesting. Makes discussion of semi-conductors and AC more relatable. Taking multiple turbulent of sources into one laminar steady-state flow is fun.

[gesamtszenario]

"There is no such thing as a positive charge carrier."
Biologists: *eye twitch*

[jerwahjwcc]

I'm over 50 and trying to teach myself a lot of these concepts and I just want to say THANK YOU. I have struggled to understand why there is a need for AA vs D cell batteries and now it makes so much sense.

[onlyeyeno]

I just want to agree with all other commenters who liked this format too, and said that it "has it's own merits" that complement Your more "elaborate demonstration videos" very well.
Best regards.

[PNWMan]

Actually I think the connected paddlewheel analogy models the transformer quite well because the primary and secondary windings are actually in phase with each other. The current in the primary winding induces a magnetic field that is 90 degrees out of phase with the current, then that same magnetic field induces a current in the secondary winding another 90 degrees out of phase making the secondary 180 degrees out of phase from the primary. The secondary can then be brought back in phase with the primary by changing the winding direction of the secondary or reversing the polarity of the output (look up the transformer dot convention).

[wbeaty]

IMPROVEMENT: your hydraulic capacitor is just adding a connection to Earth, the charge reservoir. That's not needed.
In the 1890s, Oliver Lodge figured out a water-analogy capacitor. Just use a balloon membrane, stretched across the current path. Then, whenever we "charge" the capacitor, the water stretches the rubber, storing some energy. To "discharge" the capacitor, the stretched rubber is pumping the liquid backwards. This debunks a misconception because it demonstrates that the total charge never varies inside a capacitor. (We "charge" capacitors with joules alone, not with coulombs of charge.) To add energy to a capacitor, we take charges from one plate, then insert them into the other plate. This "stretches the e-field lines." In the water-analogy, it stretches the rubber.

The MIT t.e.a.l. project for 8.02 EM classes has some great CGI e-field videos about this, one for charging, the other for discharging. Capacitors are powered by "charge-imbalance, " and by stretched-out e-fields. I tell students that capacitors "store charge" in the same way that inductors and resistors do. Meaning, they don't. Capacitors are 2-terminal components, and the path for current is THROUGH. (But in the fluid analogy, one part of the current is made of moving rubber! Heh, the rubber membrane is the Maxwell Displacement Current!)

(BElow, must first add the dot back in to addr, before the com. YT randomly deletes comments if they have URLs ...even with links to YT videos!)


Charging a 2-sphere capacitor


Discharging the capacitor

[joshinils]

I have experienced lessons about electricity and physics, but can't say I fully understood them. Certainly not to the point where I can explain what amperes are.

Because of your videos, I now know what volts are intuitively.
Emphasis on intuitively. I can explain that it's the relative difference in charge between two distinct points.

[chrisbroadhurst]

Your work and communication is fantastic - not sure I understand everything and you pose many questions that I need to find answers to. Thank you - in creditable channel

[stevievaughan]

Great vids. I use a similar water analogy when explaining how electricity obeys ohms law to my classes of apprentices. I compare the resistors to spring hinged vertical gates in the water channel. The higher the resistance is, the stronger the spring hinge is, which opposes the gate opening. Dependent on the available water pressure (voltage) this determines the amount of water (current) that flows in the circuit.

[goosar]

I still believe you could model a transformer with your trough model. Instead of connected paddle wheels, use a parallel divider wall down the center, this divider would oscillate from wall to wall (maintaining parallel). This would also create the out-of-phase motion. The voltage difference could be visualized by height of water column, and the turns ratio could be visualized by the ratio of distance between the wall and divider.

[IntenseGrid]

In the water model for inductance, you could explain that the enertia is what causes the water hammer effect, which is why we have these little air reservoirs below our faucets.

[martonlerant]

....so called hydraulic rams (aka. water hammer operated pumps) are probably the best analogy for transformers

[Scrogan]

I think a turbine pump would be closer to a constant-pressure pump, if only because it’s a Norton equivalent source with non-trivial parallel resistance.

Also your reservoir tank capacitor only works for a parallel capacitor to ground, it doesn’t work for a series capacitor. Rubber membranes are required for this.

[thestralspirit]

I quite like the informal videos! It's a good medium between not posting a video and doing a whole bunch of work to post the formalized videos

[trevorclinton]

My favorite quasiparticle is the dressed-particle. An example is an electron in a medium. Electrons in silicon are just as much fictional as holes. As proof they have a different mass than a free electron (effective mass).
Photons in a medium are similar (they travel at a different speed than free photons)

[maxwellfire]

The standard analogy that I've seen for a capacitor is a thin elastic membrane in the channel. This allows for a capacitor that isn't to ground, and the fact that DC currents can't flow through it.


The analogy ive seen for an inductor is a water wheel. I believe that if you connect this to a water wheel in another channel (optionally through a gear reduction to represent the difference in turns), you can get a pretty good model of a transformer

[Hyo]

Some feedback: 1) Can you show us how a venturi tube would look like as its analogous electrical system? 2) I think a great example of where inductors behave exactly the same in both worlds is the Water Hammer. When you close a valve, all of a sudden you get a transient spike of pressure that is so strong it can easily tear apart very thick pipes. It’s just like when you quickly stop the current going into and out of an inductor - it’s very common to blow up diodes by having an inductor force current to go through them the wrong way with the spike of voltage it assumes. 3) I think that if we see transformers as something that keeps the power in the water constant but changes the pressure, we can simply use a change in a tube’s cross section as a transformer. When the cross section is reduced, the pressure goes down but the speed goes up. The power transmitted by the water is kept constant, but we have managed to change the pressure (as well as the speed).

[juanzapata]

Hi AP, great video with very intuitive explanations. I found it very interesting, but was wondering how the scale was calculated when comparing the water model to real electricity. To find the size of the new tank, i would assume you see how many electrons are in a 1m wire, and scale that to the size of a water molecule. The part I am struggling a bit with seeing the conversion is with volts to cm of height. Since this relation works in the context of energies, is the conversion simply a matter of seeing at what distance from the earth does raising a water molecule 2cm produce an eV of potential energy? Then, would the top of the tank be at this distance from earth, and the dimensions of the tank determined by the answer to the first part? Thanks, and please keep making these!!

[iwantagoodnameplease]

Re: The water model, and also circuits in general, I'm always left puzzling about things like a tap/faucet. What is that? It's just water spilling out of the nice watery circuit and into the void of the world.

Similarly: Why can't a positive of one power source go through a bunch of resistors and then into the negative of another source? If one power source is "pumping" electrons to a higher voltage, why does it need a circuit of them? Especially as the drift velocity is really slow so the individual electrons barely move. As long as there is some supply of electrons, why does it matter that they all link up in a big circle? In theory you can stab both "open" ends of the power source into the physical earth and claim they're connected via that and now suddenly everything works, as if there's an actual direct flow between them (but also not between everything else stabbed into the earth).

In your most recent video of the time-multiplex oscilloscope animations of open circuits I can kind of see you need compression in the red wire and a decompression in the black wire... but again why does it need a circuit for the current?

It's all too mysterious for me :)