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 ).