We all have common sense notions of heat and temperature. Temperature is a measure of ‘hotness’ of a body. A kettle with boiling water is hotter than a box containing ice. In this chapter, you will learn what heat is and how it is measured, and study the various proceses by which heat flows from one body to another. You will also learn what happens when water boils or freezes, and its temperature does not change during these processes even though a great deal of heat is flowing into or out of it.
The branch dealing with the measurement of temperature is called thermometry and the devices used to measure temperature are called thermometers.
Thermal properties of a material decide how it reacts when it is subjected to heat fluctuation (excessive heat or very low heat, for example). The major components of thermal properties are:
What is Heat Capacity: Heat capacity of a material can be defined as the amount of heat required to change the temperature of the material by one degree. The amount of heat is generally expressed in joules or calories and the temperature in Celsius or Kelvin.
What is Thermal Expansion: When heat is passed through a material, its shape changes. Generally, a material expands when heated. This property of a material is called Thermal Expansion. There can be a change in the area, volume, and shape of the material. For example, railway tracks often expand and as a result, get misshapen due to extreme heat.
What is Thermal Conductivity: It is the property of a material to conduct heat through itself. Materials with high thermal conductivity will conduct more heat than the ones with low conductivity. Some materials do not conduct heat at all because of the insulating properties of materials.
What is Thermal Stress: The stress experienced by a body due to either thermal expansion or contraction is called thermal stress. It can be potentially destructive in nature as it can make the material explode.
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