1. 3 Types of Heat Transfer

2. Heat Transfer-
The movement of heat from a warmer object to a cooler object.

3. 1. Conduction Heat transfer by direct contact of molecules.
In other words, when one molecule runs into another and it runs into another, etc.
It can occur in a solid, liquid or a gas.
Occurs best in a solid because the molecules are close together.

4. conduction

5. 2. Convection
Heat transfer by means of up and down movements called convection currents.
Can occur only in a liquid or a gas

6. Convection currents Heated molecules do 2 things:
1. they expand (move apart), become less dense and then..
2. they rise.
Cooled molecules do the exact opposite:
1. they contract (get closer), become more dense and then…
2. they sink
That is what makes a hot air balloon rise.

7. 3. Radiation
Heat transfer through open space.
Occurs in a gas only.