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well we are going to take into consideration that in a motor you can

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change the source of rotation if you change the polarity in a battery. What I

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trying to say is for example if I have a very simple circuit with just only one

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motor like this and we have two now that are the same circuit but in this one we're going to change

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the polarity of the battery so we have two circuits

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that are the same, but in this one, the polarity has this sense, so the motor rotates in this sense,

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and in the other one, the polarity of the battery is changing, so the sense of rotation also is inverse.

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So, we can solve the problem if we are able to join these two circuits.

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To do that we need a special switch.

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So we are going to stop and we are going to transfer the circuit.

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have one we can do with the battery it is possible but there isn't just only

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one solution of this problem you can choose you can find different solution

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I'm going to give the one that I think is the best is using this type of switch

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this type of switch have two positions as you can see here this is one position

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and this is the other position so this kind of switch let us to join both

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circuits so we have the two position and now we have there's only one motor so in

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this position we join our motor in this way so we have sorry in this in this way

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so we have one sense of rotation so if I change this position

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don't worry sometimes happen I need to change also the polarity so now I have

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the other sense of rotation so in this position we have one

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sensor rotation and in the other we have the opposite. So it's one solution

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you also can do with two batteries and different switches, but from my point of

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view this is the best solution of this problem. Well, the next one. To understand

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the importance of the diode LED and how it works. We can do two different circuits

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similar to the motor, but in this case we need at least one resistor. The best

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value for the resistor is 220 and very careful because this is the symbol of

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lead and this is the most important thing in this case so we have the

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symbol of lead and indeed is a little bit more complicated that what I'm going

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to explain for you but I don't know I think is it's difficult to understand

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well if at the same we are going to copy and paste the same but changing changing

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the polarity well what happens in the polarity is that it the left works

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perfectly but if the polarity is inverse the LED doesn't work. It's what I want to learn

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no more because it is indeed more complicated. For example we're going to

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measure the intensity current in both circuits. Well something similar

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happens with the left. If I have a simple circuit with a battery and resistor

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this is the resistor of about 220 you can find this kind of circuit a lot of

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them searching for information on the Internet. So the circuit itself is really

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really easy. The problem is not a circuit, the problem usually is that you can

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understand what happened with the circuit, but the circuit itself is really

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easy. Firstly, in a diabolos we can have different colors and in each color is

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also difference the condition that they they must work but in any case if you

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have a good son of working for the left and the the voltage in the less resource

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is always the same is always about a oh seven a volts so we are going to do

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two different circuits with the same diode and the difference between them is

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just only the polarity in the battery. The only difference between these two

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circuits is the polarity of the battery. What happened? In the first

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case the diode works perfectly but in the second it doesn't it's enough that

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you for the moment understand this do you do you don't need to understand not

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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.

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so if you have the voltage you also can know the intensity current so a good

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exercise for you can be to use the Ohm's law in this case in in each case

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and for the moment is enough for you that if you change the polarity the

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other doesn't work it's enough for you if you want you want to do something

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more you must use Young's law to understand this case because in this

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case is is quite different other thing that can be good a good exercise if you

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want if try to change try to change the diode and know what happened with the

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intensity current and the voltage for example if I use instead a red one if I

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use a red one, you can see that the values are different. So depending on the

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diodes, the values of intensity, current and voltage are

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different. Well, can be interesting also if you want, but for the moment is enough

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with this information because as you can imagine it is more complicated than this

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so finally the resistor the value of the resistor well I added to you apart from

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the video with the difference circuit I'm going to add it a document in which

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I explain the third question of this exercise I hope it can be useful for you

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Thank you so much. In the last exercise we must know the value of this resistor using the

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color code. So we have to know the nominal value we have the three

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first band color band first is yellow so digit 4 second is orange so digit 3 and

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third is red so digit 2 so take if we have if we take into consideration the

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position of the band, it is very easy to know that the value of the resistor is 4300 ohms,

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or what is the same, 43 kilos.

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The fourth band is tolerance.

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this case is silver so its value is 10% it means that our resistor is between

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the its upper value which is its value plus the 10% of its value in this case

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the 10% is 430 and the lower value of the resistor so in our case is 10% of

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thousand three hundred so 430 so our resistor is between its upper value and

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00:17:14,779 --> 00:17:57,500
And its lower value, its upper value is 4,300 plus 330. So the result is 4,730 is its upper value.

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And its lower value is 4300, but you must to pick up the 10%.

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So, its lower value is 3080.70, and that is the exercise.