1 00:00:00,000 --> 00:00:07,160 This video series is going to be all about the basics of electricity, and I'm going to explain what amps, volts, ohms, and watts are. 2 00:00:07,580 --> 00:00:09,599 In this video, we're just going to start with amps. 3 00:00:10,359 --> 00:00:14,679 So you probably know that everything around you is made up of tiny particles called atoms. 4 00:00:15,300 --> 00:00:23,039 The simplified model of an atom has a positively charged center called the nucleus, and you have negatively charged electrons orbiting around it. 5 00:00:23,039 --> 00:00:34,039 The terms positively charged and negatively charged are arbitrary, and the important thing to know is that things with opposite charges attract each other, and things with the same charge repel each other. 6 00:00:34,039 --> 00:00:42,039 So the positive nucleus of the atom will attract negative electrons, but if electrons get too close to each other, they'll push each other away. 7 00:00:42,039 --> 00:00:48,039 In most solid materials, the atoms and their electrons just sit there and don't really move around. 8 00:00:48,039 --> 00:00:52,039 But in metals, like copper, the electrons have the ability to move around. 9 00:00:52,039 --> 00:00:56,880 The positive nuclei stay in the same place, preserving the structure of the metal, 10 00:00:57,140 --> 00:01:00,020 but the electrons can drift around from atom to atom. 11 00:01:00,859 --> 00:01:04,079 But since the negatively charged electrons repel each other, 12 00:01:04,420 --> 00:01:09,439 when you move one electron from atom to atom, you'll also move other electrons from atom to atom. 13 00:01:10,319 --> 00:01:13,819 For example, let's say you have a wire that's only one atom thick. 14 00:01:14,239 --> 00:01:19,659 And just so you know, I'm massively oversimplifying things here by showing you only one electron per atom. 15 00:01:20,519 --> 00:01:25,519 Then let's say that you force the first electron in line to jump to the second atom in line. 16 00:01:25,980 --> 00:01:30,900 The electrons will all push each other around at the same time, kind of like a conga line. 17 00:01:32,560 --> 00:01:36,420 Even though each electron is only jumping a tiny, tiny distance, 18 00:01:36,840 --> 00:01:39,700 this overall flow happens close to the speed of light. 19 00:01:40,700 --> 00:01:43,099 And that's basically what the flow of electricity is. 20 00:01:43,099 --> 00:01:47,500 When electrons are flowing through something, you can say that electric current is flowing. 21 00:01:47,500 --> 00:01:52,500 Now, how do we measure electric current? Well, you've probably heard of the term 22 00:01:52,500 --> 00:01:57,579 amp, which is short for ampere. An ampere refers to the amount of electrons that are 23 00:01:57,579 --> 00:02:03,040 flowing per second through something that conducts electricity. One ampere is equivalent 24 00:02:03,040 --> 00:02:09,039 to 6.24 times 10 to the power of 18 electrons flowing per second. You don't really need 25 00:02:09,039 --> 00:02:13,460 to memorize that number, but you should understand that electrical current refers to the amount 26 00:02:13,460 --> 00:02:18,860 of electron flow, and that 1 amp means that a lot of electrons are flowing. 27 00:02:18,860 --> 00:02:22,819 And obviously 2 amps means that twice the electrons are flowing. 28 00:02:22,819 --> 00:02:27,780 And if you want, you can use the analogy of the amount of water flowing through a pipe. 29 00:02:27,780 --> 00:02:32,340 Okay, just so you have a frame of reference, here are a few examples of different currents 30 00:02:32,340 --> 00:02:35,080 you might encounter in your day-to-day life. 31 00:02:35,080 --> 00:02:39,939 Alright, now's the perfect time to talk about electric circuits. 32 00:02:39,939 --> 00:02:44,460 An electric circuit is a closed loop where current can flow around. 33 00:02:44,460 --> 00:02:49,520 In this example of a flashlight, electrons can flow from the battery, through the copper 34 00:02:49,520 --> 00:02:54,620 wire, through the light and through another piece of wire to the other side of the battery. 35 00:02:54,620 --> 00:03:00,020 Now remember, when current is flowing here, all the electrons are moving at the same time. 36 00:03:00,020 --> 00:03:04,819 Over here, the negative terminal of the battery is pushing the negative electrons away, and 37 00:03:04,819 --> 00:03:07,879 those electrons are pushing other electrons away. 38 00:03:07,879 --> 00:03:12,219 And this keeps happening throughout the circuit, allowing energy to be transferred from the 39 00:03:12,219 --> 00:03:14,379 battery to the light. 40 00:03:14,379 --> 00:03:19,000 But if you were to cut one of the wires here, you would no longer have a complete circuit. 41 00:03:19,000 --> 00:03:22,599 The electrons can't just jump through the air from one wire to another. 42 00:03:22,599 --> 00:03:27,599 So if electrons can't push each other around in a complete loop, no current can flow. 43 00:03:27,599 --> 00:03:31,719 When there's no current flowing, there can't be any transfer of energy, so the light stays 44 00:03:31,719 --> 00:03:32,719 off. 45 00:03:32,719 --> 00:03:34,900 And this is how electric switches work. 46 00:03:34,900 --> 00:03:39,039 The switch has two pieces of metal inside it, and when the pieces of metal touch, you 47 00:03:39,039 --> 00:03:41,800 get a complete circuit, and the light turns on. 48 00:03:41,800 --> 00:03:45,419 When the pieces of metal are pulled apart, it becomes an open circuit, and the light 49 00:03:45,419 --> 00:03:47,400 turns off. 50 00:03:47,400 --> 00:03:49,539 And this is also how fuses work. 51 00:03:49,539 --> 00:03:54,960 Right now I have 5 amps flowing through this fuse, which is rated for 15 amps. 52 00:03:54,960 --> 00:03:59,819 But when I suddenly draw 30 amps, the fuse melts, opens the circuit, and prevents any 53 00:03:59,819 --> 00:04:02,979 current from flowing until the fuse is replaced. 54 00:04:02,979 --> 00:04:06,379 Very handy for when you don't want to die in a terrible fire. 55 00:04:06,379 --> 00:04:10,879 Now there's one more tricky thing about electric current that most people don't know. 56 00:04:10,879 --> 00:04:14,360 There are actually two naming systems for electric current. 57 00:04:14,360 --> 00:04:18,699 One is called conventional current and the other is called electron flow. 58 00:04:18,699 --> 00:04:21,839 You may have heard that current flows from positive to negative. 59 00:04:21,839 --> 00:04:25,699 So you might imagine that with this circuit, current is flowing from the positive side 60 00:04:25,699 --> 00:04:28,740 of the battery towards the negative side of the battery. 61 00:04:28,740 --> 00:04:33,779 This system of current flowing from positive to negative is what all electrical engineers 62 00:04:33,779 --> 00:04:36,740 use, and it's called conventional current. 63 00:04:36,740 --> 00:04:39,759 However, conventional current is wrong! 64 00:04:39,759 --> 00:04:44,339 Back in the early days when scientists were still figuring out the basics of electricity, 65 00:04:44,339 --> 00:04:48,339 they didn't know whether it was the protons or the electrons that were flowing. 66 00:04:48,339 --> 00:04:51,920 They made a guess and thought that current flowed from positive to negative, but the 67 00:04:51,920 --> 00:04:56,860 reality is that the actual flow of electrons goes from negative to positive. 68 00:04:56,860 --> 00:05:02,259 Unfortunately every single formula that we use in electronics is based around the mistake 69 00:05:02,259 --> 00:05:05,699 of assuming that current flows from positive to negative. 70 00:05:05,699 --> 00:05:10,660 The good news is that the formulas are consistent and whenever we do any math in electrical 71 00:05:10,660 --> 00:05:14,699 engineering we use this system of conventional current and it works. 72 00:05:14,699 --> 00:05:18,779 So you can just pretend that electrons are moving from positive to negative even though 73 00:05:18,779 --> 00:05:21,399 that's backwards to reality. 74 00:05:21,399 --> 00:05:25,759 Alright so amps are easy to understand, it's just the flow of electrons. 75 00:05:25,759 --> 00:05:29,259 In my next video I'm gonna explain what voltage is.