 heat capacity is amount of heat absorbed by 1 kg of substance is the amount of heat absorbed by 1 kg of 1 kg of substance increase a temperature by 1 degree Celsius. So, s should be equal to 1 delta q divided by m into delta q. Now, delta q will be equal to m s delta t by definition itself. Now, this specific heat is different for different material for iron it is something else for copper it is something else like that getting it. So, if temperature is increased heat will be absorbed if temperature is decreased same heat will be released. So, if you already know that the decreasing temperature is like release of heat and increase of temperature is absorption of heat you do not care about the sign coming in you always subtract lower temperature from higher temperature you take the modulus of it. Let us suppose changing temperature is 5 degree Celsius whether it is increase or decrease the quantum of heat is same whether it is released or absorbed. So, that is how you deal with and then you find out the heat involved in the process m s delta t any doubt here no I think this concept was introduced in class 10, 9 in chemistry m c and c v delta t that is molar specific heat. Now, this specific heat capacity is a very good you know physical parameter for liquids and for solids for gases the situation becomes little tricky. The problem is this let me give you an example suppose you are cooking a food inside a pressure cooker and suppose you are cooking food in an open utensil where the food will be cooked faster pressure cooker why because temperature increases faster inside the pressure cooker same gas is there same gas it mostly gas only is there, but it is able to increase its temperature more if it is inside the pressure cooker with the same amount of heat what is so special in the pressure cooker? The volume is constant when it is open utensil what is constant pressure is constant. So, for gases we need to also take into account that whether it is a constant volume or constant pressure process constant volume specific heat is different constant pressure it is different you learn more about it in thermodynamics what happens is that the some amount of heat with gas absorbs goes into expansion when you are allowing it to expand but when you are enclosing it it cannot do any work whatever heat you give entire heat gets converted into rise in temperature of the gas fine. So, that is the reason why same amount of heat when you good when you give in constant volume the rise in temperature is more. So, now tell me where the specific heat capacity will be more in constant volume or in constant pressure same amount of heat let us say I am giving delta q delta q at constant volume delta t will be more at constant pressure delta t is less delta q by delta t is more in constant pressure. So, at constant pressure specific heat of gas is more and when we talk about gases generally we like to deal in moles that is why the heat capacity is not defined per kg of a gas but per mole of a gas and we call it molar specific heat capacity. If you call it specific heat capacity it is still per kg only you have to specify it is molar specific heat capacity. So, what should be the formula at constant volume molar specific heat is written as C v which is equal to delta q divided by what n into delta t n is number of moles this is C v heat is supplied at constant volume C p is delta q p divided by n into delta t. So, if I give let us say one joule here delta q is one joule here also one joule which delta t will be more this or that constant volumes delta t will be more this is pressure total like scenario delta t is more temperature rise is faster. So, denominator is more than this denominator that is why this is lesser than that C v is more than C v write down calorie metering is what a unit of heat energy in a way metering is measurement it is like measuring something. So, measurement of heat is calorie metering is a process of measuring the heat. So, in the calorie metering we will learn about an experiment to measure the heat itself or this experiment will help you calculate the specific heat of particular substance. Have you ever heard of calorie metering term before you are in C v s your ice case do you see you see calorie metering uses a bucket sort of thing that is called calorie meter. So, you have this calorie meter it is made up of an insulating material you may want to put the foam inside or make it upward. You are doing it so that there is no exchange of heat from the sounding whatever happens inside remains inside then you have to put a lid also at the top and then let us say it has water. Now, you are going to measure heat. So, what is the first instrument you should have thermometer right there is a thermometer which goes like this this is thermometer you may want to open the lid and then drop a very hot iron ball inside. So, that heat is getting exchanged between iron ball and water and based on that you draw some inferences. But, when you do it when it goes down may be water this side is hotter that side water is colder temperature is not uniform then what you should need stirrer. So, you have a stirrer also it will just mix everything fine. So, this is the calorie meter inside which you have exchange of heat which is happening and the best part is there is no exchange of heat from the sounding that is assumption actually there will be some exchange of heat anyways. But, then what will happen inside the calorie meter there will be some hot objects right down there will be hot objects before mixing and talking like for example, this is a hot iron ball there will be hot objects and then there will be cold objects of course, hot and cold they are relative term. So, I am saying the temperature difference is there. So, now, when they are coming in contact and you have a stirrer also what will happen exchange of heat hot objects what they will do they will lose heat to lose heat energy and what the cold objects will do they will gain heat energy. Now, is the magnitude of loss in heat energy is equal to the magnitude of gain in heat energy yes or no it will be right this is how you this is nothing but conservation of energy only. This is how you use calorie meter to measure the heat you just equating the amount of heat that is lost by the hot object with the amount of heat that is absorbed by the colder object. Now, when you leave it like this when the hot object comes in contact with the colder object and you with the stirrer do all that and leave it for very long time what will happen temperature becomes constant both for hot as well as cold both will come at the same temperature initially they may be having different temperature but finally they will come at the same temperature it may happen that in a numerical it is given like for example X amount of heat is given out to the atmosphere then I think you are intelligent enough to equate right you can say that whatever heat hot object is releasing that is equal to gain in heat energy by the colder object plus loss to the atmosphere right but majority of the time they will not gain in loss to the atmosphere okay so all we have to do in a numerical related to calorie meter is equate loss in heat energy with gain in heat energy we lose the heat energy hot object and we will gain the heat energy colder objects very simple okay shall we do a numerical treatment for delta q is what m s delta t fine till now our assumption is we are not changing state it will never happen that right now I can you know I can put an ice also its state will change it will become liquid right I am not touching that scenario right now I am just talking about scenario where the states remains same if initial state is liquid the remain liquid if initial state is solid remains solid now tell me one thing there will be hot object there will be colder objects calorie meter is this bucket let us say okay which will have a proper coating inside will this calorie meter also absorb heat or release heat current does it can do it can right so you need to take into account the calorie meter also fine so initial temperature of calorie meter will be the temperature of all the objects inside the calorie metering initially and the final temperature of calorie meter will be the final temperature of everything which will be constant for all okay at times it will be given that calorie meters water equivalent is 100 gram what does it mean it means that calorie meter will absorb same amount of heat as if 100 gram of water would have absorbed fine understood so all these final nuances will be there in problem solving may not be at your school level but when you solve jail your question there will be such new answers okay