 I have this glass of water with some sand dissolved in it and I want to separate the sand from the water. Can I do that? It turns out there is a method to do the separation, to carry out the separation and that method is called filtration. Filtration is used to separate a solid from a liquid and in this case the solid particles they are not dissolved in water. Filtration only works for such purposes when the solid particles are not dissolved in water. Now how to carry out filtration? Let's have a look at this. So we can pour the mixture of sand and water on to this filter paper that you can see is fitted in a funnel and I have something near the bottom of the funnel which can collect the water that will come out. So when I pour the mixture, the filter paper filters out the sand particles and lets the water pass through it which is then collected in a container at the bottom and you can see that in front of you. Now this works because the filter paper has very small ports in it which can allow the water particles to pass through it but it filters out, it does not allow the bigger solid sand particles to pass through it. So all the sand is collected in the filter paper and then you get much clearer water. It might still have very small sand particles present in it but the majority of the sand particles have been filtered out. So now let's have a look at the diagram. This over here, you can see that this is the mixture of the solid and liquid. It could be anything, it could be chalk in water, even chalk does not dissolve in water, right? And when you pour this mixture onto this filter paper, this right here is the filter paper. It lets the water molecules to pass through it which is then collected at the bottom and that is called a filtrate, that is called filtrate. In this case, the filtrate is water. Whatever sand that is collected in the filter paper, that really is called residue. So this is sand in this case. Alright, now this over here is filter, this is a funnel, so let me write that as well. This is a funnel and this could be anything, you can collect the filtrate in any sort of container. It could be a conical flask, a beaker or just an everyday usable container. So this is how filtration works. It is used to separate solid from liquids and this is a kind of a physical separation. This is called a physical separation because there is no change in how the particles are arranged. Nothing new is formed, you are just separating sand from water. No new substance is formed, you are just physically separating them. And this is how filtration works.