Thermal Equilibrium (OCR A Level Physics)

Defining Thermal Equilibrium

• Thermal energy is always transferred from a hotter region to lower region

• Thermal equilibrium is defined as:

  When two substances in physical contact with each other no longer exchange any heat energy and both reach an equal temperature

• There is no longer thermal energy transfer between the regions

Two regions of different temperatures reaching thermal equilibrium after some time

• The two regions need to be in contact for this to occur

• The hotter region will cool down and the cooler region will heat up until they reach the same temperature

• The final temperature when two regions are in thermal equilibrium depends on the initial temperature difference between them

• An example of this is ice in room temperature water. The ice cubes heat up from the energy transfer from the water and the water cools down due to the ice until the water’s temperature is in thermal equilibrium