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Hot Dog Cookery

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As the experiment today we are going to be cooking hotdogs. But we're doing some physics with it. We are going to determine whether or not the hot dog obeys Ohm's law. I'm going to go ahead and put it up on the two forks here. This puts it in to a simple circuit which I'll tell you about right now. Our simple circuit just consists of a power supply and the hotdog. We're not using regular battery but we're coming straight from the power company. And the reason we're doing that is because it takes quite a bit of current to cook this hot dog. But, there's a safety consideration that we have to take into account here. Once I plug this in then we have AC current running through our setup. Okay if I were to take a hold of these two forks at the same time then I would have that electric current running through my body and I would be electrocuted, not a good thing. Alright so it's very important that I have a system that I use to make sure I don't accidentally do something dumb like that. So here's my system. The power strip right here is turned off right now. When I have everything ready to go and I'm ready to start cooking that hotdog then I'm going to plug in the cord right here and then I'm going to move around to the front and I'm going to turn the power strip on. And at that point until I turn the power strip off again I won't touch anything that's on the table. And my cameraman Trevor here part of his job besides filming this whole thing is to make sure that I don't do something dumb and touch the table when I'm not supposed to.

Alright so, not to plug in yet, let me tell you a little bit more about the circuit and then we will go about doing the experiment. My simple circuit I said just has the circuit or battery which is the power company and the circuit element which is the hotdog. But, we also have two meters because we want to measure current and voltage at the same time. This meter is hooked up to measure the voltage at the same time. This meter is hooked up to measure the voltage across the hot dog, while this meter is hooked up to measure the current through the hotdog. Now we need those simultaneous measures because we're going to do a graph of current vs. voltage and from that determine whether or not the hotdog obeys Ohm's law. Now here's the way the experiment will work, soon as I flip the switch we record the time which will be zero, and record the current reading and the voltage reading. Every fifteen seconds we'll read voltage and current. Yyou can record those on your paper as we go or you can play back the video later as we do that. Then once the hotdog is cooked and there will be a signal the hotdog will do something to make it clear to us that it really is cooked. At that point I turn off the power strip and we'll have our data.

Okay, I'll move around to the front of the table and we'll get ready to take data. Okay, once again here is the current meter here is the volt meter. And, I'm going to plug in and when the second hand reaches the clock I'm going to turn on. Here we go: Voltage reading is 124; current reading is 1.00 A. We're coming up on the 15 second mark here; the voltage is 123 the current is 1.36. The current is going up rapidly so I'm trying to guess at what it is on the time box. We're coming up at 30 seconds, at 30 seconds voltage 122.8, current 1.65. Current's not going up as quickly now; its creeping up slowly. Coming up on 45 seconds. The voltage is 123, the current is 1.52, almost at one minute. One minute voltage at 123.4, current at 1.22. Alright, next 15 seconds, 123.5 current 1.04, currents going down now. Watch keep your eyes peeled for something, Okay voltage 126, current has dropped to .04. Alright there was a very sudden drop in the current right there. Alright I have to turn off the power strip, unplug, and now I can touch the stuff that's on the table again. Alright so you may have noticed that, I don't know if you can hear the hotdog sizzling but I could hear it sizzling pretty good. But when that current made a sudden drop there, at the very end, the sizzling stopped. So that can give you a clue about the physical processes that are going on, and how that affects the resistance of the hot dog as it cooks. So, you have your data now you can take it and there will be a set of questions on the web that you'll answer in order to complete the analysis of this laboratory.



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