Electricity is magic

Miscellaneous and Personal Stuff I Must Share
1

This is where I confess that I don’t understand electricity. My dad understood it, and made money with that understanding. My big brother understood it by the age of eight. Me, I have a brain that refuses to grasp anything other than a few facts, and those facts are full of contradictions and subject to huge quantities of brain-fog.

I know there’s Direct Current and Alternating Current, and each has its advantages and disadvantages. I know that we use AC in our homes because it’s better at transmission over long distances, but why that is is baffling. AC goes forward and backward, forward and backward, 60 times a second depending on where you live. But if electricity can move through power lines at not-quite the speed of light, there must be a problem with, the farther you get from the power station, the more the electricity going one way must run into the electricity going the other way! That can’t be good.

I know there are amperes, which you could think of as “pieces of electricity” that just sit there, useless until you apply volts to them to push them along. But what is a volt? “Oh, that’s just a measurement.” Sorry, not helpful. I want to know where the volts are in my 9-volt battery.

Ohms. “A measurement of resistance”. I sort of get it. Watts? No idea. How does a 40 watt lightbulb know how to draw only so much elactricity, and a brighter 100 watt bulb draws more? Isn’t the source of the electricity the Boss of how much goes where?

This is really just scratching the surface. I can’t figure out a circuit, or understand why some things are wired “in series” and others “in parallel” other that if you use Series on Christmas tree lights, if one bulb dies they all go out. Everyone knows that. But I don’t see why, if you have a bunch of bulbs in series, the first bulb isn’t the brightest and each one after that isn’t dimmer, as the electricity is used up?

I fully expect helpful people to jump in here and explain all this and a lot more with a jolly eye-roll. Please don’t bother. My mind has high resistance - I might go “oh NOW I get it”, but it’s all pretend. It will quickly slide away. You and my brother get this stuff, I don’t and never will. Sorry.

2

Here’s a good explanation of the basics:

3

Yeah, I saw a version of that cartoon once, long ago with Augie Ampere (“How’m I going to get through that skinny little wire?”) and Victor Volt. That pretty much is the limit of my understanding. The drawing was a lot better in those days.

4

As we say in the electrician business: it’s all FM.

5

Well, that would happen if the mobile charge carriers (the mobile electrons in the wires in this case) “carried” energy and then transferred their energies to the bulbs as they were going down the wire. But that’s not what is really happening; the energy is not being “carried” by the electrons.

6

Well.

7

Ok, so imagine you have a wall, and you’re dropping stuff off of it. The wall is 110 inches (volts) high. If you push a BB off, it goes plink. If you push a bowling ball off, it goes BANG. How does it know how loud to be? The 40 watt bulb has more resistance, it’s a blocker that only lets small things fall off the wall, the 100 watt bulb has less resistance, it lets bigger stuff fall off the wall.

If you short circuit the socket, it lets EVERYTHING fall off at once, until the circuit breaker cuts off the supply of stuff.

8

So basically the 40 watt bulb is just wasting expensive electricity that YOU paid for, is that it?

So if the 40 watt bulb has more resistance, why doesn’t it run hotter, whereas we all know the 100 watt bulb you can barely touch. At minimum they should both be roughly the same temperature, no?

9

You have to understand a bit about voltage and current to understand why this is true.

The typical comparison (which isn’t 100 percent accurate but helps to understand the concept) is that if you have a water hose, the “voltage” is equivalent to the water pressure and the “current” is how fast the water is actually moving. In any given situation, they tend to be related. If you have higher water pressure, you end up with the water moving faster through the same size hose.

The cartoon that @Llama_Llogophile posted is basically saying the same thing.

Let’s take the simple case of an old fashioned incandescent light bulb, since this type of light bulb is basically a simple resistor. Wires aren’t superconductors, so wires also have a resistance. If you have a really long wire, the resistance of the wire can be bigger than the resistance of your light bulb. So what happens is more power gets wasted as heat in the wire than gets to your light bulb. That’s bad. You want as much power as possible getting to your light bulb.

The next thing that you need to understand is the AC transformer. This is a simple device. It’s literally just two coils of wire around an iron core. This increases or decreases the voltage based on the number of turns of each wire. In other words, if one coil of wire has 10 times as many turns around that iron core as the other wire, the transformer will increase or decrease (depending on which way you hook it up) the voltage by a factor of 10. But transformers can’t defy physics. They don’t generate power out of thin air. So if you boost the voltage by a factor of 10, the current goes down by factor of 10.

So imagine this system. You have your AC generator. You connect it to an AC transformer that boosts the voltage by a factor of 10. You transmit that across your long wire. Then at the other end, you have another AC transformer that reduces the voltage by a factor of 10. Now you are back to your original voltage, and you can connect that to your light bulb.

But if you end up with the same voltage, what’s the point of doing all of that increasing and decreasing the voltage? Here’s the thing. The power that gets converted into waste heat in the wires is proportional to the square of the current (the formula is literally i2R). So if you reduce the current in the wire by a factor of 10 in the wire between the two transformers, you decrease the power lost as waste heat by a factor of 100. That’s pretty significant.

So why don’t we do this with direct current (DC)? The simple answer is that there is no easy equivalent of an AC transformer for DC. Back in the old days, you could connect a DC motor to a DC generator and use that to change the voltage, but that’s big, clunky, expensive, and loses a lot of energy to mechanical friction. In modern times we can use semiconductor circuits, but for large amounts of power those are much more expensive than a simple AC transformer.

But we do actually use DC for long distance power transmission. It’s usually only done over very long distances with very large amounts of power, otherwise the cost of the DC “transformers” and switchgear is way too expensive and the system costs too much. But DC does have advantages, which I can talk about if you want.

So with your electrical service, a big AC generator takes power from somewhere (heat from burning coal, natural gas, or nuclear fusion to generate steam in a steam turbine, for example) and converts that into electricity, that electricity goes into big AC transformers which boost the voltage up to a very high “transmission voltage” level (50,000 to 200,000 volts or more) which keeps the losses in the wire down to a minimum. At a substation, the voltage is reduced by more AC transformers down to “distribution voltage”, which is typically somewhere between 3,000 and 12,000 volts. Distribution wires aren’t going such long distances, so they don’t need to be as high of voltage. The distribution wires run all through your neighborhood, with more AC transformers all over the place. Each of these smaller AC transformers gives power to typically 3 or 4 houses at most, and drops the voltage down to the final split 240 volt power that you get into your house.

If you tried to do that with DC back in Edison’s day, the cost of the DC motor-generator sets and inefficiencies in the system would prevent the system from being practical. That’s why Edison lost to Westinghouse, and that’s why we use AC in our homes today.

10

As if things weren’t confusing enough, please explain the Funny Joke.

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Moderator Note

Moved from IMHO to MPSIMS at the OP’s request, since it was originally intended for MPSIMS.

12

I love that cartoon!

I have a very basic understanding of electricity.

I made a neat lamp with parts from a bigger lamp that was too heavy for the mounting hook I had.

I made a long string of light emitting diodes that went in a translucent staff and could be turned on and off by stamping the base of the staff on the ground. I got the LED’s to flash on and off by stealing somebody else’s work, I took a button that had flashing LED’s and soldered wires to the battery compartment contacts and soldered wire to the leads for the LED’s included in the button. It worked but was bulky and the wires were under a lot of physical stress. They kept coming loose. Radio Shack still had a small spot devoted to electric components. I bought a flashing LED and installed it in series.

So far as I know, the movers left that staff behind.

13

You only pay for the stuff that falls off the wall, not the stuff that’s just sitting up there.

The 40 watt bulb has more resistance, it lets less stuff through, the 100 watt bulb lets 2.5x as much through, so a lot more stuff falls down and releases its energy.

14

Farkin magic.

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About the only part of this I get is that Westinghouse beat Edison. The transformer stuff is pretty fuzzy as to the how and why. But I am glad that there isn’t 200,000 volts coming into my house. So thanks for your reply.

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A little less crude than I remember, but yes.

17

It might also be helpful to think of a transformer as mechanical gearing, where you can change the force and speed of axles based on the ratio of the radiuses.

18

Don’t feel bad if you don’t “get it.” I’ve been doing electrical/electronics stuff for over four decades, and I still have problems trying to understand many aspects of it. It took me a good twenty years to even begin to develop an intuition for it. I will never master it; I will always be a student of it.

But don’t let that dissuade you. Start by trying to understand how to calculate things like voltage, current, resistance, etc. for simple circuits, and go from there. In other words, there’s a fair bit of “shut up and do the math” aspect to it, with a deeper understanding coming later.

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This is where the stream gets really muddy. “Think of electricity as water in a hose being regulated by pressure, except it’s not really like that. No wait, it’s like gears and you can step it up or down like in your car but here’s where the metaphor breaks down.”
Trying to explain the unexplainable by comparisons that have built-in limitations.

20

Let me just mention that it took until Nov. 14, 2007 for NYC to fully convert to AC power. And Con Edison had to provide converters to DC for buildings that needed DC power, say to run the elevators. In 1962, I had a girl friend who lived in such a building and she and her roommates had a DC powered AC generator sitting in closet to provide power for their appliances that required them (such as audio equipment). It was quite noisy. She lived around 100tth and B’way. At 113th, I had AC only.