The Biggest Misconception About Electricity

This video was sponsored by Caséta by Lutron. Imagine you have a giant circuit consisting of a battery, a switch, a light bulb, and two wires which are each 300,000 kilometers long. That is the distance light travels in one second. So, they would reach out half way to the moon

So, they would reach out half way to the moon and then come back to be connected to the light bulb, which is one meter away. Now, the question is, after I close this switch, how long would it take for the bulb to light up. Is it half a second, one second, two seconds, 1/c seconds,

one second, two seconds, 1/c seconds, or none of the above. You have to make some simplifying assumptions about this circuit, like the wires have to have no resistance, otherwise this wouldn't work and the light bulb has to turn on immediately when current passes through it. But I want you to commit to an answer

when current passes through it. But I want you to commit to an answer and put it down in the comments so you can't say, yeah I knew that was the answer, when I tell you the answer later on. This question relates to how electrical energy get from a power plant to your home.

get from a power plant to your home. Unlike a battery, the electricity in the grid comes in the form of alternating current, or AC, which means electrons in the power lines are just wiggling back and forth. They never go anywhere. So, if the charges don't come from the power plant

So, if the charges don't come from the power plant to your home, how does the electrical energy reach you? When I used to teach this subject, I would say that power lines are like this flexible plastic tubing and the electrons inside are like this chain.

and the electrons inside are like this chain. So, what a power station does, is it pushes and pulls the electrons back and forth 60 times a second. Now, at your house, you can plug in a device, like a toaster, which essentially means allowing the electrons to run through it.

which essentially means allowing the electrons to run through it. So when the power station pushes and pulls the electrons, well, they encounter resistance in the toaster element, and they dissipate their energy as heat, and so you can toast your bread. Now, this is a great story,

and so you can toast your bread. Now, this is a great story, I think it's easy to visualize, and I think my students understood it. The only problem is, it's wrong. For one thing, there is no continuous conducting wire that runs all the way from a power station to your house. No, there are physical gaps,

No, there are physical gaps, there are breaks in the line, like in transformers where one coil of wire is wrapped on one side, a different coil of wire is wrapped on the other side. So, electrons cannot possibly flow from one the other. Plus, if it's the electrons that are carrying the energy

Plus, if it's the electrons that are carrying the energy from the power station to your device, then when those same electrons flow back to the power station, why are they not also carrying energy back from your house to the power station? If the flow of current is two ways,

If the flow of current is two ways, then why does energy only flow in one direction? These are the lies you were taught about electricity, that electrons themselves have potential energy, that they are pushed or pulled through a continuous conducting loop

that they are pushed or pulled through a continuous conducting loop and that they dissipate their energy in the device. My claim in this video is that all of that is false. So, how does it work? In the 1860's and 70's,

In the 1860's and 70's, there was a huge breakthrough in our understanding of the universe when Scottish physicist, James Clerk Maxwell, realized that light is made up of oscillating electric and magnetic fields. The fields are oscillating perpendicular to each other and they are in phase,

The fields are oscillating perpendicular to each other and they are in phase, meaning when one is at its maximum, so is the other wave. Now, he works out the equations that govern the behavior of electric and magnetic fields and hence, these waves, those are now called Maxwell's equations.

and hence, these waves, those are now called Maxwell's equations. But in 1883, one of Maxwell's former students, John Henry Poynting, is thinking about conversation of energy. If energy is conserved locally in every tiny bit of space, well, then you should be able to trace the path

well, then you should be able to trace the path that energy flows from one place to another. So, think about the energy that comes to us from the sun, during those eight minutes when the light is traveling, the energy is stored and being transmitted in the electric and magnetic fields of the light.

in the electric and magnetic fields of the light. Now, Poynting works out an equation to describe energy flux, that is, how much electromagnetic energy is passing through an area per second. This is known as the Poynting vector and it's given the symbol S.