Ohm'sches Gesetz & Widerstände - REMAKE
Physik - simpleclub
https://www.youtube.com/watch?v=xklPZ1tzNTc

Transkript (automatisch erstellt)

0:00 Hey guys, I'm sure you all know the feeling. The washing machine, the laptop, and Grandma's old vacuum are
0:07 all on one outlet, and suddenly the fuse blows. You'll find out why that happens now. Today we're covering Ohm's
0:20 law and explaining what a resistor is. Let's just get started. You can think of a resistor as an opponent to current
0:27 . Basically, imagine that when current flows through a resistor, it gets slowed down a little. What was current
0:35 intensity again? Current indicates how many electrons flow through a conductor in a certain amount of time. And
0:42 voltage is the force that makes the electrons move through the conductor. This drives them from one point to
0:49 another, and the higher the resistance, the lower the current. By the way, resistance is abbreviated with a
0:56 capital R and its unit is Ohms. It's represented by Omega, this symbol here. But what does a resistor actually look
1:05 like? This part here is, for example, a resistor for engineers to tinker with, but actually every electronic device is
1:12 a resistor. More on that at the end. So , we now know what a resistor actually is. But why do we actually need it?
1:20 We'll explain that to you. Now let's get to Ohm's law. What Ohm's law is, is a physical law that another intelligent
1:28 brain came up with, and his last name was Ohm. Sounds logical, right? And what does the law state? It states that
1:37 there is a relationship between voltage U and the current I flowing through the conductor. Specifically, U and I are
1:44 proportional to each other. But what does that mean exactly? If we increase the voltage in a simple circuit, the
1:51 current also increases. So, more current flows the higher the voltage is . We can imagine it like this. We have
1:59 a small wooden board, which represents our conductor. We place a few marbles on the board to represent our electrons
2:05 . They can move freely in any direction . If we lift the board on one side, all the marbles move in one direction,
2:13 downwards. That is essentially our current direction. The current then corresponds to the time it takes for
2:19 the marbles to roll down. If we lift the board higher, the marbles roll down faster. The height at which we lift the
2:27 board corresponds to the voltage in our circuit. The higher we lift the board, the faster the marbles move, and the
2:34 higher our voltage, the higher our current. Now let's go a step further and hammer nails all over our board. We
2:42 can compare the nails to our resistance . We put our marbles back on and lift the board on one side. You can surely
2:50 guess what happens now. The marbles move downward, just much more slowly. They keep hitting the nails and are
2:57 slowed down as a result. The more nails we add, the longer it would take for the marbles to reach the bottom. So the
3:04 resistance would increase and the current would keep decreasing. And that is exactly how it works in an
3:09 electrical circuit. The electrons are slowed down by the resistance. This changes the current, and we can of
3:16 course put the whole thing into a formula. It is R = U divided by I. R is the resistance. We already know what U
3:24 is, namely voltage, and I is, as always , current. You should definitely memorize this formula well. And to make
3:31 this formula easier to remember, there is the magic triangle. You draw a triangle and write a U at the top and R
3:38 times I at the bottom. If you now want to calculate one of the values, simply cross out the corresponding letter and
3:44 you can then read off the formula for it. Here is a small example. We have a voltage of 10 volts and a current of 2
3:53 amperes. How big is our resistance now? To calculate that, we just take our triangle and cross out the R. We can
4:01 now read off the formula quite easily. So R is U divided by I. Let's plug in our values, so R = 10 divided by 2. And
4:10 that is clearly 5 ohms. All right. It's that simple. Great, then we've covered almost everything now, but one question
4:18 remains open. What about the fuse? Why does it trip when we plug all our devices into one outlet? We can now
4:26 explain that quite easily with Ohm's law. Every electronic device is a resistor because they need current to
4:32 run. The voltage in the socket is always 230 volts. Now we plug a few devices into our socket. The voltage
4:40 stays the same. But the total resistance becomes smaller. That's because we have a parallel circuit of
4:46 resistors here. The devices are not connected in series, but in parallel. This means we add the reciprocal of all
4:53 resistors, and that makes the total resistance smaller. That's a bit complicated. To understand that, just
4:59 check out our video on series and parallel circuits of resistors. So we now have a lower resistance while the
5:06 voltage remains the same. This results in a higher current, because if there are fewer nails in our board, the balls
5:13 can roll down faster. At some point, the current reaches 16 amps. And to prevent overloading the circuit, the
5:19 fuse in the basement blows and all the lights in the house go out. Let's summarize everything briefly and
5:26 concisely. Resistance represents the ratio between voltage and the flowing current. So, what voltage is needed to
5:33 allow a certain current to flow through a conductor? Resistance has the symbol R and the unit ohm. Ohm's law states
5:41 that voltage U and current I are proportional to each other. This means that if we increase the voltage in a
5:48 circuit, the current flowing through it also increases. And to calculate all of this, we just need to remember this
5:54 nice triangle. Hi, this is Nico from Simpleclub. Are you also tired of clicking through
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