In this IIT JEE video lectures of physics, we are going to discuss the topic calorimetry. In the given video we are going to discuss temperature, thermal equilibrium or zeroth law, thermometers and Celsius temperature scale, the triple point of water, Celsius, Fahrenheit and Kelvin temperature scale.

In the beginning jee physics lecture, we have discussed temperature. Most, of the students, think that objects that are hot are at a higher temperature and objects which are cold are at a lower temperature. But my dear aspiring IITians that is the wrong explanation of temperature. Temperature can be defined in two ways,

1. Thermodynamics: According to this, the temperature is a thermodynamic potential.
2. Kinetic theory of gasses: According to this, the temperature is a measure of kinetic energy of an ideal gas.

The next topic discussed is thermal equilibrium which is also known as the Zeroth law. According to this law, there is no flow of heat and heat flows from higher to lower temperature and not vice versa.

We have also discussed three cases related to it in the above video.

The statement of the Zeroth law is, “If First and Second body are in thermal equilibrium with each other. If second body is also in thermal equilibrium with third body, then we first and third are also in thermal equilibrium”. Further, we have discussed the ice point of water which is zero degrees and the boiling point of water is a hundred degrees.  Next, we have discussed the triple point of water. The triple point of water is nothing but the temperature at which water co-exists in all the three stages (solid, liquid, gas).

The final topic in the video lecture discussed is Celsius, Fahrenheit, and Celsius scale. In the above video, we have derived the relation between Celsius, Fahrenheit and Kelvin scale. The boiling point of water in Celsius scale is 100⁰C and the freezing point is 0⁰C. The boiling point of water in Fahrenheit scale is 212⁰F and the freezing point is 32⁰F. The boiling point of water in Kelvin scale is 373.15K and the freezing point is 273.15K. 