AC vs. DC

welcome to our second video on electricity this one is going to be on alternating and direct currents so our goals from this video or one be able to explain the difference between alternating and direct currents and later on we're actually going to analyze the pros and cons of each the first kind of we're going to talk about is direct current direct current is what we call uni-directional and what that means it only goes one way it's like a one-way road or a one-way street this is just like batteries and circuits or anything with your remote controls and your Xbox Playstation and anything like that so if we take a look down here at the bottom we have our battery in our circuit the battery emits electrons they flow through they keep going and they go through this one way they just keep cycling through this one path that's all they do one way you need directional this is made famous by Thomas Edison Thomas Edison is the one that really tried to use this with their houses and almost powering towns with it he almost did it exclusively with direct current but what happened is this man came along and his name was Nikola Tesla and he came up with this thing called alternating current Nikola Tesla actually now has a car named after him the the Tesla so alternating currents a little bit different as its name States it alternates back and forth it's bi-directional two directions goes back and forth alternates back and forth left right left right this is what we use in our houses today and we use what's called sixty Hertz which means that it alternates it flips 60 times per second not per minute per second so the electricity switches 60 times per second and we can see that with our little lab activities here so we're going to first go to direct current one path if you take a look at the electrons here this is using our little FET activity pH et you can see the electrons are going one way just one direction that's it there's no fancy alternating back and forth this one direction there's here's a little skeleton energizer alternating current on the other hand switches back and forth and we can see that over here you can see the electrons don't really move very far but they're alternating back and forth back and forth remember this is a scaled version these electrons would actually be going so much faster the one thing you probably see that's different is these light bulbs these light bulbs are flashing they're not steadily on like our direct current what the difference is is that when these switch directions for a fraction of a second they're actually stopped they're dead stopped but inside the light bulb stays glowing for that fraction of a second the light stays there you don't tell you can't see the difference in between on and off that quickly so remember we talked about alternating current is 60 Hertz it changes 60 times per second this our little AC battery here is only going about one time every second it's changing one time every second we can bump it up to two times a second that's the most that the program can hold so we can see that they're flashing a lot quicker now now imagine this times 30 you wouldn't be able to tell the difference between flashing or on and off it would just be constant on and that's what happens in your houses you can't tell the difference between on and off you can't tell the difference but you can't tell when the electrons are switching back and forth so we're going to jump to another program in a second I'm going to show you how this is done and we can remember that like forces repel each other electrons repel electrons and opposite forces attract each other so we've been talking about magnets a little bit in alternating current is made with very big magnets moving very quickly and we're going to go to our program over here and this is a magnet here North Pole South Pole you can kind of think of this as positive negative here's a wire coil with electrons in it if we start moving this magnet it starts to move the electrons back and forth if you follow them they go back and forth the magnet moves them so this is how power companies work with alternating current they have a giant magnet that rotates very quickly and it moves the electrons and wires nearby this is how alternating current is made so once again you can see the lightbulbs flashing nothing very special if we crank this up quite a bit to a hundred revolutions per minute it's getting harder to see when it's off now this is going at a hundred rpms per minute to get to sixty Hertz which is sixty times per second so we have to figure that one out it's 60 times per second and this is in minutes so we take 60 times 60 and it actually comes out to be three thousand six hundred revolutions per minute so we would have to multiply this by thirty six times to get the actual speed of what a magnet travels that in a real power company just someone to think about with how electricity is made and brought from a power company into your house so you can cook your hot pocket okay this is what you're going to need to know from today's little talk and video Direct Current one direction DC alternating current AC switches back and forth those are the simple ideas that we've gone over today you're also going to need to know how alternating current is made with that spinning magnet and knowing that like forces repel each other and opposite forces attract and the last thing everybody needs to know is AC DC is one of the best bands ever and thank you very much to the University of Colorado for allowing me to use their Phet interactive simulations I've put the link to their website below which has dozens of great simulations

Channel: Chris Mahl

Views: 1,509,194

Rating: 4.7929163 out of 5

Keywords: Alternating Current (Invention), Direct Current (Electric Current Type), Nikola Tesla (Author)

Id: BcIDRet787k

Length: 6min 23sec (383 seconds)

Published: Wed Jan 15 2014