 So, today we are going to start this chapter thermal properties of matter, so this is the first chapter of study of heat and its phenomena, writing it. Now, this is the entire section in physics where you study about thermal properties of matter, then you learn about how you convert heat energy into work in thermodynamics and then you get into the details of exactly how the velocity of the molecules can contribute to pressure or can contribute to energy. So, you exactly get to know what are the micro factors what is happening because of which the temperature is increased for a particular you know substance, so all that will constitute inside a big chunk of your class 11, which is you know thermodynamic from property of matter and kinetic theory of gases, so this constitutes in and around 10 to 15 percent of your you know let us say J syllabus as such, so a good number of questions come from this section and the best part is what it is very easy and that is probably the another reason why a student take it for granted and they will be like I will be doing it at the end let me do the difficult part first, what happens because of that is your difficult part never improves and you use out on the easy part also, so make sure you are very good at thermodynamics which is probably the easiest section of your class 11 fine, so be very attentive in class anywhere whenever you have doubt please feel free to ask make sure you are very very good at this entire section. This study of heat and its phenomena this has been done for ages now, in fact you know when people have started understanding about physics as a branch, they have studied first about the heavenly objects like stars, sun and all that, so aschnoming was considered to be the oldest branch of science and later on when the fire was discovered and they came to know something heat is one of the form of energy then the study of heat also picked up, the study of mechanics sorry study of the motion of object and then study of rigid body and all that came much later on, so thermodynamics is one of the oldest branch of science where we study the heat and its phenomena, so the first chapter in that series write down is thermal properties, so you will see in your book number 2, you are essentially learning about properties of different things, first chapter is what mechanical properties of solids, then what mechanical properties of fluids, now thermal properties of matter, so we are not studying thermal properties of solids separately and thermal properties of liquids separately okay because with respect to thermal properties they are behaving in a similar way fine, so entire matters thermal property is what we are going to learn in this particular chapter okay, now can you tell me, first of all tell me what do we mean by property, property means what like for example what's your name? Aditya, like suppose if I talk about what are the properties of Aditya, so what will come in my mind as in something which is very specific to Aditya, isn't it right, I will not say that Aditya is a student okay, that's the generic thing, so when I say property of anything a specific thing will come in my mind alright, so now when I say thermal properties of matter, thermal properties of matter, so what should come in my mind, something which get affected by something related to heat or temperature, some properties that are related with heat and temperature, can you tell me few properties which are related to heat and temperature for a particular substance, pressure of a gas is related with the temperature okay, what else, volume does it depend on the temperature, does it change, if I change the temperature does volume change, it changes right, so expansion, expansion of an object is a thermal property okay, that we are going to learn in this particular section okay, so write down property number one, the first property, this is what thermal property of matter, so we are just listing down what are those thermal properties okay, the first brand property is thermal expansion, so we will get into the details of it, right now we are just focusing on what could be the properties that we should focus on okay, this is one of the properties, any doubt here okay, it says that whenever you heat any object, increase its temperature, its volume will increase alright, what else can you think of anything else, this is the first property, second one, the temperature is the cause okay, now see why this thermal expansion is a property because two different substances will expand differently for a given change in temperature okay, so it's a unique property, expansion of one object is different from the other object for a given temperature change, so that is why it is a property, had it been that all the object expand equally with the same amount of temperature change then it is not a property of a object okay, now can you think of any other property other than thermal expansion, state, now what do you mean by state, state of matter, liquid, gas or solid, now is that a thermal property, if I let's say heat up an object, a solid object, will its state change after some time, depends but then it will eventually convert into liquid, isn't it and then it will convert into vapor like what happens with water, its ice and then it melts and then evaporates and that happens because you're giving it heat right, now can you tell me is that a property of a substance, can two substances, they require different amount of heat to change their states right, they require like for example if you heat up an iron object, it will require much more heat to melt than melting ice, getting it, so state change is second property, so what I mean by state change is solid converting into liquid and then converting into vapor, different amount of heat is required to change the state from one state to the other state for different objects, so that is why it is a property, now can you think of any other property, just think a lot I mean it's okay if you're wrong, what do you mean by heat capacity, okay now suppose you have two objects, if I give let's say same amount of heat to both the objects, will the change in temperature be same, should it be same for both the object, not necessary right, suppose you give let's say 5 joules of heat to a very good conductor of heat, it's temperature will immediately increase, okay but if you give the same amount of heat to a bad conductor of heat, it will not increase very fast, so there has to be some term defined which takes care of the fact as in how much heat is required to increase the temperature, so the best way to quantify this property is heat required per degree change in temperature, which will be different for different objects, yes or no, right and that property heat required to change per degree temperature is heat capacity, fine so the third property is heat capacity, this is heat required divided by however much temperature as reason because of that, different object will have different heat capacity, okay we will come back to specific heat capacity later on, right now we are just defining heat capacity that is more generate than specific heat capacity, okay now can you think of fourth property now, property number four what do you think change in energy is taken care by this, latent heat is taken care by this, latent heat is required to change the state that will be different for different options, okay fourth property I just give you a hint suppose you are cooking food in a proper utensil or suppose you are cooking food in stainless steel where the food will be cooked faster, how fast heat is conducted from one point to the other point, is that a property, that is a property, right for example if there is some hot object if you try to touch it through an iron rod the heat will conduct to you at a much faster rate than if you just poke it with a bad conductor of heat, okay so how fast heat is getting conducted that itself is a property of a substance, okay so the fourth property is heat transfer which is nothing but the rate of transfer of heat energy, okay any doubts, these are the four properties that we are going to learn in this chapter one by one, okay so we will take property number one initially,