1 00:00:01,010 --> 00:00:17,010 Well, we are going to take into consideration that in a motor you can change the zones of rotation if you change the polarity in a battery. 2 00:00:17,010 --> 00:00:28,699 What I'm trying to say is, for example, if I have very simple circuits with just only one motor, like this, 3 00:00:28,699 --> 00:01:09,959 and we have two now that are the same circuit but in this one we're going to 4 00:01:09,959 --> 00:01:25,819 change the polarity of the battery so we have two circuits that are the same but 5 00:01:25,819 --> 00:01:39,159 But in this one, the polarity has this sense, so the motor rotates in this sense, and in 6 00:01:39,159 --> 00:01:49,239 the other one, the polarity of the battery is changing, so the sense of rotation also 7 00:01:49,239 --> 00:01:51,120 is inverse. 8 00:01:51,120 --> 00:02:03,680 So we can solve the problem if we are able to join these two circuits. 9 00:02:03,680 --> 00:02:09,300 To do that we need a special switch. 10 00:02:09,300 --> 00:02:21,580 So we are going to stop and we are going to transfer the circuit. 11 00:02:21,580 --> 00:02:33,400 have one we can do with the battery it is possible but there isn't just only 12 00:02:33,400 --> 00:02:39,139 one solution of this problem you can choose to can find different solution 13 00:02:39,139 --> 00:02:48,199 I'm going to give the one that I think is the best is using this type of switch 14 00:02:48,199 --> 00:03:00,069 This type of switch have two positions, as you can see here this is one position and 15 00:03:00,069 --> 00:03:03,050 this is the other position. 16 00:03:03,050 --> 00:03:13,449 So this kind of switch let us to join both circuits. 17 00:03:13,449 --> 00:03:22,949 So we have the two positions and now we have just only one motor. 18 00:03:22,949 --> 00:03:39,919 So in this position we join our motor in this way. 19 00:03:39,919 --> 00:04:00,199 So we have, sorry, in this way. 20 00:04:00,199 --> 00:04:04,639 So we have one sense of rotation. 21 00:04:04,639 --> 00:04:18,339 So if I change this position, don't worry, it sometimes happens, I need to change also 22 00:04:18,339 --> 00:04:35,490 the polarity, so now I have the other sense of rotation. 23 00:04:35,490 --> 00:04:42,470 So in this position we have one sense of rotation, and in the other we have the opposite. 24 00:04:42,470 --> 00:04:51,430 So each one is one solution, you also can do with two batteries and different switches. 25 00:04:51,430 --> 00:04:56,709 But from my point of view, this is the best solution of this problem. 26 00:04:56,709 --> 00:05:22,569 Well, the next one, to understand, well, something similar happens with the lift. 27 00:05:22,569 --> 00:05:30,970 If I have a simple circuit with a battery and a resistor, this is a resistor of about 28 00:05:30,970 --> 00:05:41,310 220, you can find this kind of circuit, a lot of them, searching for information on 29 00:05:41,310 --> 00:05:43,129 the internet. 30 00:05:43,129 --> 00:05:47,990 So the circuit itself is really, really easy. 31 00:05:47,990 --> 00:05:49,410 The problem is not the circuit. 32 00:05:49,410 --> 00:05:57,250 The problem usually is that you can't understand what happened with the circuit, but the circuit 33 00:05:57,250 --> 00:06:16,850 itself is really easy. 34 00:06:16,850 --> 00:06:28,089 Well, firstly, in a dielolith we can have different colors, and in each color is also 35 00:06:28,089 --> 00:06:34,569 different the condition that they must work. 36 00:06:34,569 --> 00:06:47,490 But in any case, if you have a good zone of working for the LED, the voltage in the LED 37 00:06:47,490 --> 00:06:55,529 is always the same, it's always about 0.7 volts. 38 00:06:55,529 --> 00:07:12,709 So we are going to do two different circuits with the same diode, and the difference between 39 00:07:12,709 --> 00:07:41,350 them is just only the polarity in the battery. 40 00:07:41,350 --> 00:07:56,449 The only difference between these two circuits is the polarity of the battery. 41 00:07:56,449 --> 00:07:57,449 What happens? 42 00:07:57,449 --> 00:08:13,930 In the first case, the diode works perfectly, but in the second, it doesn't. It's enough that you, for the moment, understand this. 43 00:08:13,930 --> 00:09:03,830 You don't need to understand, no, but if you want, if I connect a voltimeter in parallel with the diodo, in each case, you can know the voltage in this case. 44 00:09:03,830 --> 00:09:27,139 So if you have the voltage, you also can know the intensity current. 45 00:09:27,139 --> 00:09:36,919 So a good exercise for you can be to use the Ohm's law in this case, in each case. 46 00:09:36,919 --> 00:09:44,059 And for the moment, it's enough for you that if you change the polarity, the diode doesn't 47 00:09:44,059 --> 00:09:45,059 work. 48 00:09:45,059 --> 00:09:46,059 It's enough for you. 49 00:09:46,059 --> 00:09:57,879 If you want to do something more, you must use Young's Law to understand this case, because 50 00:09:57,879 --> 00:10:02,259 in this case it's quite different. 51 00:10:02,259 --> 00:10:13,240 Another thing that can be good, a good exercise if you want, is try to change, try to change 52 00:10:13,240 --> 00:10:22,840 the diode and know what happened with the intensity current and the voltage. 53 00:10:22,840 --> 00:10:47,769 For example, if I use instead a red one, if I use a red one, you can see that the values 54 00:10:47,769 --> 00:10:49,710 are different. 55 00:10:49,710 --> 00:10:59,409 So depending of the diode, the point, the values of intensity, current and voltage are 56 00:10:59,409 --> 00:11:00,409 different. 57 00:11:00,409 --> 00:11:11,409 Well, it can be interesting also if you want, but for the moment is enough with this information. 58 00:11:11,409 --> 00:11:21,409 Because, as you can imagine, it is more complicated than this. 59 00:11:21,409 --> 00:11:49,360 So, finally, the resistor, the value of the resistor. Well, I added to you, apart from the video with the difference resistor, you see the color code. 60 00:11:49,360 --> 00:12:12,679 So we have, to know the nominal value, we have the three first bands, color bands. First is yellow, so digit 4. Second is orange, so digit 3. And third is red, so digit 2. 61 00:12:12,679 --> 00:12:25,240 So, if we take into consideration the position of the band, it is very easy to know that 62 00:12:25,240 --> 00:12:40,879 the value of the resistor is 4300 ohms, or what is the same, 43 kilos. 63 00:12:40,879 --> 00:12:52,100 The fourth band is tolerance, in this case is silver, so its value is 10%. 64 00:12:52,100 --> 00:13:07,019 It means that our resistor is between its upper value, which is its value plus the 10% 65 00:13:07,019 --> 00:13:22,620 this value in this case the 10% is 430 and the lower value of the resistor so 66 00:13:22,620 --> 00:13:42,779 in our case is 10% of 3300 so 430 so our resistor is between its upper value and 67 00:13:42,779 --> 00:14:25,549 And its lower value, its upper value is 4,300 plus 330. So the result is 4,730 is its upper value. 68 00:14:25,549 --> 00:14:51,159 And its lower value is 4300, but you must to pick up the 10%. 69 00:14:51,159 --> 00:15:12,009 So, its lower value is 3080.70, and that is the exercise.