What causes it?

Hey!
Today I'll be sharing more about the transfer of thermal energy.
Like I promised.

Anyways, as you can see from the title,
today I'll be talking about the CAUSES of thermal energy!
What causes this transfer?
Aren't you all curious! :D

Firstly, some key points about the transfer of thermal energy that we need to know:

1) Thermal energy is transfered only when there is a difference in temperature.
2) Thermal energy always flows from a region of higher temperature to a region of lower temperature.

These 2 facts can be proved by a simple experiment.

The set up would be:
Prepare 3 small basins of water of 3 different temperatures. One basin with hot water, maybe of 50degrees celcius, another one at body temperature, about 37degrees celcius and another with cold water, maybe about 10degrees celcius. We shall label these basins A, B and C respectively. Next, place your right hand in basin C, with the cold water while also placing your left hand in Basin A, the basin of hot water, at the same time. You would come to realize that you left hand would feel hot in the hot water, while your right hand would feel cold in the cold water. After a while, remove both hands, dry them with a cloth and then wait for the effects of hotness and coldness in your hands to subside. Then, place one hand, any hand, into Basin B. Your hand would feel neither hot or cold. (37degrees celcius is body temperature)

Why is this so?

This simple experiment proves the 2 key points of the transfer of thermal energy so well.

Point 1 is proven, as from this simple experiment, it is clearly shown that is it possible to feel whether you hands are feeling hot or cold as there is a temperature difference.

Point 2 is also proven in this experiment as your left hand only feels hot because it gains thermal energy from the hot water in Basin A; and your right hand feels cold because it loses thermal energy to the cold water in Basin C.

Also, from the experiment, we can also learn another thing about the transfer of thermal energy, which would be about THERMAL EQUILIBRIUM.

Which brings us to this point:
3) When a thermal equilibrium is reached between two bodies, meaning that both bodies are of the same temperature, there is no net flow of thermal energy between them.

We can see that this point is true when your hands feel neither hot or cold in Basin B, where the temperature of the water is the same as body temperature. Here, thermal equilibrium is reached as there is no net gain or loss of thermal energy between the water in Basin B and your hands.

Which ends of this part about the causes of thermal energy (: