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Subido el 14 de abril de 2020 por Isabel L.

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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. 00:00:01
What I'm trying to say is, for example, if I have very simple circuits with just only one motor, like this, 00:00:17
and we have two now that are the same circuit but in this one we're going to 00:00:28
change the polarity of the battery so we have two circuits that are the same but 00:01:09
But in this one, the polarity has this sense, so the motor rotates in this sense, and in 00:01:25
the other one, the polarity of the battery is changing, so the sense of rotation also 00:01:39
is inverse. 00:01:49
So we can solve the problem if we are able to join these two circuits. 00:01:51
To do that we need a special switch. 00:02:03
So we are going to stop and we are going to transfer the circuit. 00:02:09
have one we can do with the battery it is possible but there isn't just only 00:02:21
one solution of this problem you can choose to can find different solution 00:02:33
I'm going to give the one that I think is the best is using this type of switch 00:02:39
This type of switch have two positions, as you can see here this is one position and 00:02:48
this is the other position. 00:03:00
So this kind of switch let us to join both circuits. 00:03:03
So we have the two positions and now we have just only one motor. 00:03:13
So in this position we join our motor in this way. 00:03:22
So we have, sorry, in this way. 00:03:39
So we have one sense of rotation. 00:04:00
So if I change this position, don't worry, it sometimes happens, I need to change also 00:04:04
the polarity, so now I have the other sense of rotation. 00:04:18
So in this position we have one sense of rotation, and in the other we have the opposite. 00:04:35
So each one is one solution, you also can do with two batteries and different switches. 00:04:42
But from my point of view, this is the best solution of this problem. 00:04:51
Well, the next one, to understand, well, something similar happens with the lift. 00:04:56
If I have a simple circuit with a battery and a resistor, this is a resistor of about 00:05:22
220, you can find this kind of circuit, a lot of them, searching for information on 00:05:30
the internet. 00:05:41
So the circuit itself is really, really easy. 00:05:43
The problem is not the circuit. 00:05:47
The problem usually is that you can't understand what happened with the circuit, but the circuit 00:05:49
itself is really easy. 00:05:57
Well, firstly, in a dielolith we can have different colors, and in each color is also 00:06:16
different the condition that they must work. 00:06:28
But in any case, if you have a good zone of working for the LED, the voltage in the LED 00:06:34
is always the same, it's always about 0.7 volts. 00:06:47
So we are going to do two different circuits with the same diode, and the difference between 00:06:55
them is just only the polarity in the battery. 00:07:12
The only difference between these two circuits is the polarity of the battery. 00:07:41
What happens? 00:07:56
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. 00:07:57
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. 00:08:13
So if you have the voltage, you also can know the intensity current. 00:09:03
So a good exercise for you can be to use the Ohm's law in this case, in each case. 00:09:27
And for the moment, it's enough for you that if you change the polarity, the diode doesn't 00:09:36
work. 00:09:44
It's enough for you. 00:09:45
If you want to do something more, you must use Young's Law to understand this case, because 00:09:46
in this case it's quite different. 00:09:57
Another thing that can be good, a good exercise if you want, is try to change, try to change 00:10:02
the diode and know what happened with the intensity current and the voltage. 00:10:13
For example, if I use instead a red one, if I use a red one, you can see that the values 00:10:22
are different. 00:10:47
So depending of the diode, the point, the values of intensity, current and voltage are 00:10:49
different. 00:10:59
Well, it can be interesting also if you want, but for the moment is enough with this information. 00:11:00
Because, as you can imagine, it is more complicated than this. 00:11:11
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. 00:11:21
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. 00:11:49
So, if we take into consideration the position of the band, it is very easy to know that 00:12:12
the value of the resistor is 4300 ohms, or what is the same, 43 kilos. 00:12:25
The fourth band is tolerance, in this case is silver, so its value is 10%. 00:12:40
It means that our resistor is between its upper value, which is its value plus the 10% 00:12:52
this value in this case the 10% is 430 and the lower value of the resistor so 00:13:07
in our case is 10% of 3300 so 430 so our resistor is between its upper value and 00:13:22
And its lower value, its upper value is 4,300 plus 330. So the result is 4,730 is its upper value. 00:13:42
And its lower value is 4300, but you must to pick up the 10%. 00:14:25
So, its lower value is 3080.70, and that is the exercise. 00:14:51
Idioma/s:
en
Autor/es:
Isabel Lafuente Reboredo
Subido por:
Isabel L.
Licencia:
Reconocimiento - No comercial
Visualizaciones:
97
Fecha:
14 de abril de 2020 - 17:58
Visibilidad:
Público
Centro:
IES JOSÉ GARCÍA NIETO
Duración:
15′ 20″
Relación de aspecto:
1.78:1
Resolución:
1920x1080 píxeles
Tamaño:
165.17 MBytes

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