The branch dealing with measurement of temperature is called thermometry and the devices used to measure temperature are called thermometers.
Heat
Heat is a form of energy called thermal energy which flows from a higher temperature body to a lower temperature body when they are placed in contact.
Heat or thermal energy of a body is the sum of kinetic energies of all its constituent particles, on account of translational, vibrational and rotational motion.
The SI unit of heat energy is joule( J). The practical unit of heat energy is calorie. 1 cal = 4.18 J
1 calorie is the quantity of heat required to raise the temperature of 1 g of water by 1 ° C.
Mechanical energy or work( W) can be converted into heat( Q) by 1 W = JQ
where J = Joule’ s mechanical equivalent of heat. J is a conversion factor( not a physical quantity) and its value is 4.186 J / cal.
Temperature
Temperature of a body is the degree of hotness or coldness of the body. A device which is used to measure the temperature, is called a thermometer.
Highest possible temperature achieved in laboratory is about 108 while lowest possible temperature attained is 10-8 K.
Branch of Physics dealing with production and measurement temperature close to 0 K is known as cryagenics, while that deaf with the measurement of very high temperature is called pyromet Temperature of the core of the sun is 107 K while that of its surface 6000 K.
NTP or STP implies 273.15 K( 0 ° C = 32 ° F).