We often refer to infrared radiation as being primarily heat (or thermal) radiation. But what exactly is heat, and how does it differ from temperature? Simply put, heat is a measurement
of energy. All molecules contain some amount of kinetic energy, that is to say, they have
some intrinsic motion. Hence the question What Is The Difference Between Heat And Temperature
The hotter an object is, the faster the motion of the molecules inside
it. Thus, the heat of an object is the total energy of all the molecular motion inside that object.
Temperature, on the other hand, is a measure of the average heat or thermal energy of the
molecules in a substance.
When we say an object has a temperature of 100 degrees C, for
example, we do not mean that every single molecule has that exact thermal energy. In any
substance, molecules are moving with a range of energies, and interacting with each other
as well, which changes their energies. But if we average the thermal energies of all the mol-
ecules together, we can obtain an object’s temperature.
Heat and Temperature
Heat and temperature are not the same thing, they in fact mean two different things;
- Temperature is related to how fast the atoms within a substance are moving.
- Heat is a measure of how many atoms there are in a substance multiplied by how much energy each atom possesses.
So for example there is more heat in an ice cube than in a flame.
Why? Because although the atoms in an ice cube are moving about three times slower than the atoms in a flame, there are around 1000 times more atoms in an ice cube than in a flame!
It is normal to make an analogy with water.
Water ‘flows’ when there is a difference in the ‘levels’ of water in different places. It doesn’t matter if there is more water in one place or another. Water from a puddle can flow into a reservoir or the other way around. The ‘temperature’ of an object is like the water level – it determines the direction in which ‘heat’ will flow.