Thermal energy naturally transfers from hotter to colder objects through three main methods: (1) Conduction, where energy transfers through direct contact of particles in substances or between substances; (2) Convection, where the flow of fluids like gases or liquids transfers energy; and (3) Radiation, where electromagnetic waves transfer energy without requiring contact between objects. Technologies like furnaces and refrigerators control the rate of heating and cooling through these thermal energy transfer methods.

1. Thermal Energy Transfer
Study Notes
Thermal Energy naturally moves
from a substance with a higher
temperature to a substance with a
lower temperature, until the two
substances have the same
temperature

2. Humans have invented many technologies that transfer energy
from one object to another or from one place to another.
For example, we use furnaces to heat our homes, and refrigerators
to cool our food.
Technology allows us to control the rate of heating and cooling
but not reverse its direction.

3. Conduction
•Conduction is the transfer of thermal energy
through a substance, or between substances in
contact
•This energy is caused by the collision of the fast
moving particles(hot object) with the slower
moving particles(cold object).
•Conductors, such as metal, transfer energy easily.
Insulators such as foam or wood, reduce the
transfer of energy.
•Think about your coffee keeper. What did you do
to stop the transfer of energy through conduction.

4. Convection
•Convection is the transfer of thermal energy
caused by the flow of a fluids particles (gas or
liquid).
•The continuous movement of warmer and
colder soup in a pot is an example of convection.
•The hot, less dense soup moves up to the
surface where it cools. The cool soup is now
more dense and sinks back to the bottom of the
pot. The movement creates convection
currents.

5. Convection in the environment
•Just as uneven heating of soup on a stove can produce
convection currents, uneven heating of the air can produce
convection currents called “wind.”
•Near a lake, the air above the water is colder than the air above
the land. The warm air particles above the land move faster
and spread apart. This makes the air above the land less dense
(lighter) than the air over the water.
•Thunderstorms, ocean currents and the movement of the
earth’s crust also result from convection currents.

6. Radiation
•Radiant energy is the energy that travels in the form of
electromagnetic waves, including visible light, ultraviolet
rays and x-rays, for example.
•Radiation is the transfer of radiant energy by means of
electromagnetic waves.
•Unlike the other two ways of transferring thermal energy,
•Particles are not involved in the transfer of radiant energy,
meaning radiant energy may travel through empty space.
•Sources of radiant energy include the sun, candle flames,
and stove elements, for example

7. •Think about your coffee
keeper. What did you do to
stop the transfer of thermal
energy. Which type(s) of heat
transfer did your invention
best slow down. Explain how?