Temperature and heat

Temperature

Temperature is an intensive property that indicates the thermal state of a system or a body. Temperature is a measure of internal energy possessed by a system and gives the direction in which energy in the form of heat will flow. It is generally denoted by ‘T’ and following scales are used to measure temperature

Celsius or Centigrade Scale: According to this scale the freezing point of water is assigned a value of zero and boiling point value is 100. It is represented by degree celcius.

Kelvin Scale: According to this scale the freezing point of water is assigned a value of 273 and boiling point value is 373. It is represented by K.

Fahrenheit Scale: According to this scale the freezing point of water is assigned a value of 32 and boiling point value is 212. It is represented by degree Fahrenheit.

The relationship between these three scales of temperature measurement is given as

The relationship between three scales of temperature measurement

Heat

Heat is a form of energy which is transient in nature and it flows from one point to another point. When two bodies of different temperatures come in contact with each other, the two temperatures approach each other and after some time become equal. This equalization of temperature of the bodies is on account of flow of energy in the form of heat from one body to another. Therefore, heat may be defined as flow of energy from one body to another body by virtue of temperature difference between them. The net flow of energy always occurs from high temperature body towards low temperature body and this flow of heat stops the moment temperature of both the bodies are equal. Thus, flow of heat is a non-mechanical transfer of energy occurring due to a temperature difference between two bodies.

According to the international system of units (S.I.), the unit of measurement of heat is Joule.

1 Joule = 1 Newton meter = Watt-second

1 kcal = 4.182 Χ 103 Joule

1 kWh = 3600 kJ