 Let's see how to figure out magnetic fields you to current carrying loops. So here's the first example, I have a current that's going in a circular loop this way. I want to know what the magnetic field looks like everywhere at the center and what the magnetic field looks like as I go away from the center. How do I do this? For this we're going to use our right hand thumb rule which basically says if the four fingers over here represent the direction of the looping current as you can see direction of the looping current then the thumb will represent the direction of the magnetic field at the center. So just from this I now understand that the magnetic field at the center must be pointing upwards. This immediately means that this loop starts acting like a tiny bar magnet with the north pole up and the south pole down. So you can also think of the thumb pointing the north pole. Since the thumb is pointing up it's saying that the north pole must also be pointing up. And now how does the magnetic field vary as we go away? Well just like with the bar magnet as I go away from the center the magnetic field starts curving. So this is what it would look like. You see as I go away the magnetic field starts curving the direction stays put it curves even more and eventually at this point it becomes a circle. In fact these will eventually loop all the magnetic field lines will actually become loops which I've not shown over here. But over here eventually you can see this start becoming more and more circular. And notice the direction the direction continues it's the same direction and then it becomes circular like this. All right let's try one more. Why don't you pause the video and think about how the magnetic field looks like again at the center. And if you can imagine a tiny bar magnet where would the north pole be pointing why don't you pause and try. All right again the trick is to use your right hand in such a way that the four encircling fingers represent the direction of the current. See the current looping. And when you do that notice the thumb points out of the screen towards us which means the magnetic field must be pointing out of the screen towards us. And that's what the field direction looks like. I've drawn that in a little bit of 3D so you can see it's coming out of the screen towards us. This means the north pole must also be out of the screen towards us because the thumb points towards the north pole. So if you were to imagine the tiny bar magnet this is what it will look like. And now how does the field look like as I go away from the center we'll just start curving and very similar to this it'll start curving and eventually loop. And I know it's a little hard to see from this angle so here's the thing what if we could look at the whole thing from the top. Let me redraw that over here. Okay you imagine that this point A where the loop is where the current is entering into it this is that point A and then the loop point B where the current is coming out here's that point B. So what would the magnetic field look like? Well if I were to look at it from the top the same thing now you can see much better. The same thing magnetic field coming out of the screen from the top it looks like this downwards curves curves and then eventually starts looping. Again remember these are all looping of course but the loop becomes smaller and smaller and eventually you can see these loops. And so if you had some iron filings over here those iron filings would also align themselves according to the magnetic field.