in today's video we're going to learn about magnets and specifically how we represent magnetic fields using field lines now a magnet is any material or object that produces a magnetic field the most common type of magnet you'll see is probably the bar magnets but they actually come in all shapes and sizes from these simple horseshoe magnets to the entire earth itself which is basically one huge magnet what all magnets have in common though is that they have two poles a north and a south and they're surrounded by a magnetic field in order to properly represent these magnetic fields we use something called field lines which are effectively arrows that you draw around your magnet from the north pole to the south pole and it's important that you can draw these lines for your exam and you put the arrows in the right places the easiest way to do this is to draw at least one straight line going into the south pole and coming out of the north pole then a pair going into the south pole that are slightly curved and a similar pair coming out of the north and then lastly some of the loop all the way around from the north to south as well as these basic lines you could add in some more arrows if you want to in the same style but you generally don't need to for example and the last thing you want to do is double check all of your little arrows on the lines are pointing the right way because we want our arrows to go out of the north and into the south the benefit of representing our magnetic field with lines like this is not only that it shows us where the field is and which direction it's acting in but that it also shows us the relative strength of the field in different places because the more dense the field lines are which is to say the closer together the lines are the stronger the magnetic field is in that area for example we can see that the field will be much stronger over here by the north pole than it would out here to the side because this one by the pole has lots more lines going through it now in real life we obviously can't see the field lines and magnets aren't always labeled with a north and south however we can easily find the poles and field lines by using a compass this works because the needle of a compass is actually a tiny bar magnet and will always line up with the field lines of whichever magnetic field is put in and it will also always point towards a south pole of a magnet so if we put our compass over here near our magnet we could draw an arrow in the same direction as the compass needle and as it's heading towards this magnet we know that this must be the south pole whereas if we place the compass over here then our compass needle would be pointing away from the magnet so this must be the magnet's north pole by doing this over and over again in different places we would eventually recreate the same pattern as our field line diagram from before so to get our field lines all we need to do is join up our arrows and if you want to see how this works in real life we've linked a live video of it down below in the description the last thing we need to look at is how to show the interaction between two different file magnets as you know if you push the north poles of two magnets together then they'll repel each other which is what makes it hard to squeeze them together we can see why this is if we draw the field lines between them it's this interaction of the magnetic fields that creates the force of proportion on the other hand if we flipped one of our magnets around and brought two opposite poles close together then they would attract one another because all the field lines would be going from north to south and so be attractive anyway that's all for this video today so hope you enjoyed it and we'll see you next time you