Now, in this video we will talk about the types of system because by now we have understood what is a thermodynamic system and what are thermodynamics? So, let us start by understanding the type of system that we have. The first type of system that we have is an open system. The second kind of system that we have is a closed system and the third kind of system that we have is an isolated system. Let me write down one more kind of system but we will discuss about that at the end of all these three systems and that is an adiabatic system. Okay, adiabatic system. We will come to that at the end of this video. Okay, so let us first of all understand the difference that lies between open, closed and isolated system. All right, as I told you that in thermodynamics we deal with energy interaction. So, energy interaction can be in the form of heat interaction, work interaction. Okay, and there is also some inflow around flow of mass happening in a particular system. So, if you talk about an open system, open means that there is no restriction to the inflow and outflow of the energy 2m from the system and also there is no restriction of the inflow and outflow of mass 2m from the system. So, if you draw a diagram or a schematic to understand and to define the open system. So, this is how you can draw it. So, this is the schematic of an open system. Okay, you have some mass which comes in, mass which comes in, you have some mass which goes out. All right, and this red dotted line becomes the system boundary. Okay, so this is my open system. Okay, through which mass can flow in and you know go out also you have energy which can go in and go out. So, let me create some heat in flow or let us put it energy. Let us not particularly look at only heat only. So, let us say energy in and you have some energy out. Okay, so you have both mass and energy going in and out of the system. So, this becomes an open system. All right, now let us come to closed. In closed system you have the energy interaction taking place 2m from the system but there is no mass inflow and outflow. So, for example, if you take a pest and cylinder arrangement, so let me draw one for you. So, this is a rigid cylinder and a pest and inside it, this is the pest and it is okay, this is the pest. Now, in this your system is the volume of gases which is entrapped inside the pest and the cylinder arrangement that is on top of the pest and below the cylinder head. So, this is the system that we have that we are observing for thermodynamics study. So, this is the system. Okay, now you can see that this volume of gases or this volume of gas can either accept heat from the outside or some energy from the outside or it can reject the energy or heat to the surroundings. So, this is energy in and this is energy out. But as you can see that the volume, the mass of the gases, not volume, but only mass, volume can you know change, it can expand, it can you can say be compressed. So, the mass of the gases inside this arrangement will not change. Okay, so in a very simplified manner we can say that this mass, inflow and outflow which is happening in the open system is not a part of the closed system. So, there is no mass inflow or outflow. So, I can say mass in, mass out. This is 0. Nothing is going in, nothing is going out. So, whatever that you know that is there in the system before you start observing it, it will stay at the end of the analysis also. So, there is no mass in flow or outflow, but there is some energy in flow and energy outflow. All right. Now, let us go to the next kind of the system which is called the isolated system. Now, what is an isolated system? Now, first of all an isolated system is a special kind of closed system. So, these two are linked because isolated there is a special case of closed. Okay. So, what is happening? In a closed system there is no mass in flow and outflow. Nothing is going in, nothing is going out in terms of mass, but there is something which is going in and there is something which is going out in terms of the energy. But if I am able to reduce these energy interactions also to 0 that is energy which is going in becomes equal to energy which is going out which is equal to 0. Nothing is going in, nothing is going out in terms of mass and energy then it becomes an isolated system. So, you can see isolated system is a special case of closed system. Why is it linked? Because we base this on no mass in flow or outflow from the system. So, yes it is a kind of a closed system, but a special one because there is no energy interaction to and from the system as well. So, in a closed system which does not have any energy interaction to and from the system is called an isolated system. I hope you understood this concept not a very difficult one. Now, I had also talked about another kind of system which I do not call the fourth kind of system, but it is also a special case like the isolated one and that is the adiabatic system. Now, what is an adiabatic system? Now, adiabatic system is a special case of an open system. So, you can link the adiabatic and the open system. Let us link these two. All right. Now, as you saw in the isolated case, we put a restriction on the flow of energy in the closed system, is that it? So, there is no if we restrict the energy interaction to and from the system in a closed system, it becomes isolated. Now, what do we have to restrict in the open system to make it adiabatic? A very good question. Now, see in an open system you can have mass in and mass out. Yes, that will happen in the adiabatic system also, but the restriction lies only in the form of heat interaction. You have energy interaction. Yes, there will be energy interaction in adiabatic system also, but the only restriction will be in the interaction of heat to and from the system. There is no heat interaction to and from the system. So, this is zero only. So, energy restriction or energy interaction is only there in the form of work or some other form of energy, but not in the form of heat. So, if you restrict the outflow and inflow or the interaction of system with this surrounding or vice versa for heat, for an open system, it becomes an adiabatic system. So, this is a very, very simple concept to understand. Now, if you take some examples of the adiabatic system. So, for example, if I take a water pump. So, this can be water pump. Where in water is coming in water is going out. You put some energy into the pump and some energy is being thrown out in the system in the surroundings. Now, if you talk about adiabatic systems, let me take a case of a turbine in particular a steam turbine. So, let us take the case of a steam turbine. Now, there is steam turbine on the boundary. It is insulated. So, there is some insulation at the boundary of the turbine. So, whatever steam or whatever heat that the steam brings in, this is steam coming in and this is steam going out. I would not call it steam, but it is more of a condensate, a mixture of steam and water. So, there is some mass influence, some mass outflow. So, this makes it an open system. All right. Now, you also have a shaft over here and an alternator which produces some electricity provided that the steam turbine is a part of a, you can say power generation plant. Now, when this mass inflow happens, so this steam imparts some part of its energy to the turbine blades. So, these blades are mounted on the turbine shaft which produces some shaft work output. So, there is an energy interaction taking place in terms of work output from the system, but there is no heat loss which is occurring from the turbine casing because it has insulated. So, this becomes an adiabatic process. All right. So, this is something that you need to understand between adiabatic and open system. So, adiabatic becomes a special case of open system. All right. So, I hope you understood the different kind of systems that we have for thermodynamic analysis. Now, after this, let us discuss in the next video about macroscopic and microscopic points of view.