Activa JavaScript para disfrutar de los vídeos de la Mediateca.

tpr2_u4: circuit_ohmslaw2 - Contenido educativo

El ajuste de pantalla se aprecia al ver el vídeo en pantalla completa. Elige la presentación que más te guste:

Subido el 27 de marzo de 2020 por Maximino R.

57 visualizaciones

How to measure current through a lamp in a parallel circuit

Okay, in order to finish the measurement of the electric values, voltage, resistance and current, I'm going to complete the activity by mounting circuit 0.5 with the data we got when we did the paper activity 18 and using the same simulator 00:00:00

So, in activity 18 we had a parallel circuit with a 5 volt battery and three different lamps 00:00:27

The resistances of each lamp are 10, 25 and 5 ohms 00:00:39

So, the first thing I'm going to do is to mount the circuit 00:00:46

So, we need a parallel circuit with three resistors 00:00:50

One, two and three 00:00:54

And complete the circuit by adding some wires 00:00:56

These wires 00:01:01

Here, there and this one 00:01:03

Let's see if the circuit works 00:01:08

Ok, the circuit is working 00:01:12

Now I need to change the resistances 00:01:15

And we said that they were 00:01:21

Let's see again, 10, 25 and 5, ok, 10 ohms, 25 and 5, and the battery is a 5 volt battery, ok 00:01:23

Now we need to activate the multimeter and in this case we need to use it as an ammeter, clicking there 00:01:42

It says here, we need to read this, that to measure currents, we need to drag the probes, this and this one, onto the test point immediately before the branch 00:01:51

The branches of a parallel circuit are these, one branch, another branch, another branch 00:02:04

In a series circuit, we only have one single branch 00:02:11

So, to measure the current through lamp through resistor number 1 00:02:16

We need to open the circuit in this branch 00:02:27

Let's see how 00:02:30

So, first we draw, we drag the probe onto this point 00:02:32

And we have two green dots 00:02:38

I'm going to measure the current through this branch or this other branch 00:02:42

I'm going to measure the current through this resistor 00:02:47

So I place the probe there 00:02:50

And now I see that we have an open circuit here 00:02:53

When we close the circuit 00:02:58

We see the current through this resistor 00:03:01

Look, when the current comes out of the positive terminal of the battery 00:03:04

Goes through this path 00:03:09

this pathway, go up to this point 00:03:12

then continue through the probe 00:03:16

enters the ammeter, goes out of the 00:03:19

ammeter and continue through the circuit, ok? 00:03:24

that is the way that ammeter 00:03:28

measures current, so now we have 00:03:32

0.5 amps, let's see here what we had 00:03:36

The same, 0.5 amps 00:03:40

Let's see if we have the other measurements 00:03:44

Ok, I'm going to measure now the same here in this branch, the second line 00:03:47

So I place the probe there and this here 00:03:53

The same thing, we have an open circuit here 00:03:58

But it's not a real one because in between these two points we have the ammeter 00:04:03

And now what we have is 0.2 amps 00:04:10

Ok 00:04:15

For the last one, instead of placing the probe here 00:04:16

I'm going to use this branch 00:04:21

Because it's exactly the same branch 00:04:23

As you can see here 00:04:26

This branch is the same as this 00:04:27

So I place the probe there 00:04:30

And it says 1 amp 00:04:33

Let's see here 00:04:36

1 amp 00:04:38

So, it works. The total current through the circuit, I mean the current that the battery generates, is through this branch, through these wires. So, I can check that measuring the current through this branch. 00:04:39

Ok, let's see 00:04:58

Here, the red probe 00:05:00

And now, to measure the current through this other branch 00:05:04

I need to place it there 00:05:07

But I was saying the total current 00:05:09

And the total current has to be 00:05:12

0.5 plus 0.2 plus 1 00:05:14

1.7 amps 00:05:19

Let's see 00:05:21

exactly 00:05:23

1.7 amps 00:05:26

in total 00:05:30