This learning sequence is about Faraday's law of induction. You may recall earlier in the class, I told you that Faraday was the greatest scientist that has ever lived, I stand by that. Let me tell you a little bit about why. Faraday was not born wealthy like most scientists, he was born working class. His destiny was to just take elementary school and then be apprenticed to a bookbinder, and to make books. There's nothing wrong with that. But he got very interested in science from lectures about the Royal Society, the public lectures they would give. He'd get excited and read about it, and think about, and have his own ideas, and do experiments, and show them to the scientists at the Royal Society, and say, "Hey, I want to get involved." They said, "Yeah, wherever, go away." He bugged them and eventually they let him be the janitor. He was the janitor of the Royal Society. But once he had his foot in the door, that's all he really needed because he was such a brilliant experimentalist. What's interesting about Faraday is, he didn't really know much math. He could add, and subtract, and multiply, and divide, and maybe a little algebra, but he certainly didn't know any calculus. But despite not knowing any math, he basically invented field theory. He could always think of the right experiment to do to figure what's going on in a visualized field. He called them the lines of force. Surely, we can understand fields, if Faraday understood fields because he didn't even know much math. He was very big in the early days of figuring out electricity and magnetism. Then he got off in consulting. As soon as Faraday goes off and starts doing consulting to make a lot of money, everything goes crazy. Let's look at the 1820s. What's going on in the 1820s? Well, they knew that you could get from electricity to magnetism. This is what Oersted show, we did the demo ourselves. If you have a wire with some current, it makes the magnet move. We know we can make magnetic fields with current. But that's really not what you want. Where you want that, that's fine. But what you really want is the other way because currently at this time, the main sources of electricity are triboelectricity, so rubbing cats, wind source machines, things like that, and batteries. Batteries are big and messy. These lead-acid batteries they had then that we still use today are not really convenient. It would be nice if there were some way to go the other way. Can we go from magnetism and get electricity? It would seem like we should be able to because they seem related. A lot of experimentalists were setting up things like this. Here's a bunch of loops, we know magnetism likes loops. Here's a bunch of loops of wire going to something that really sensitively measures currents and voltages, and electricity. They just wanted to say, "Is there anything I can do with this magnet to generate electricity?" It say, "Well, let's put the magnet inside the coil and let's check. Nothing." Then it say, "Okay, well, may if we put the other end inside, and see if we get anything." No, I get nothing. Maybe if we put it in here, we'll see something. Then we have checked. No, nothing. Nobody could figure out if there was a link between electricity and magnetism. Why do we just set it on the outside and then the field goes in? We have a look. Yeah, can't do it, nobody can figure it out. Then after a while, Faraday had had enough consulting. He wanted to get back into research, he wanted to work on a problem. He said, "I'm going to find this link between magnetism and electricity." Everyone said, "No, we tried that for 10 years, don't bother." He said, "No, I'm going to figure it out." He goes on vacation and starts doing his own windings, making his own instruments. He was really good at experiments, making instruments. He had the most sensitive galvanometer of anyone around. Winds all these coils up. He doesn't set up this exact experiment, it's something of a different experiment he did. But basically, he did this. There it is. You've got to look when you're making the change. Faraday's law of induction depends on a change in the magnetic field, not just having a magnetic field near the coils. Because he looked at the right time, but really more because his instrument was one of the only one sensitive enough to really see the deflection, he was the one that found the link between getting from magnetism to electricity. It has to do with being able to have a magnetic field change inside of a coil. Let's look at Faraday's law of induction.
