Transfer of Thermal (heat) Energy
Heat is a form of energy. Heat (energy) can be transferred or MOVED
from one thing to another.
Examples of thermal energy being transferred: In each of these
examples heat is being transferred from one thing to another, but is
being transferred in a different way (through radiation, conduction or
convection).
 If you are outside on a hot day and you get warm from the sun
(radiation)
 If you touch the hot blacktop, your bare feet will feel the heat
(conduction)
 If water is boiled on a stove, bubbles can be seen moving in the
pot (convection).
There THREE methods of transferring heat from one thing to another
are:
1. Radiation
2. Conduction
3. Convection
1. RADIATION
Radiation is the transfer of heat from a distance. Heat travels
from the sun to the Earth by a process called radiation. The
objects (sun and Earth) DO NOT COME IN DIRECT CONTACT
with one another.
 The sun gives off energy. It can be moved to me on a warm, sunny
day when I go outside. The closer the sun or other heat source, the
stronger the energy.
 Being warmed from a fire is another example of heat transfer
through radiation.
 In addition to the sun, some other things that radiate heat include:
light bulbs, a fire in a fireplace and toasters.
2. CONDUCTION
Conduction is a way that heat is transferred between objects
that are in direct contact.
Conduction is the transfer of energy from one particle to
another. This occurs when particles hit against one another.
Conduction is the strongest in solids because the particles are so
close together.
Metals are good conductors of heat. Wood and plastics are NOT
good conductors.
Examples of Conduction:
The burner on the stove is heating the frying pan because it is in direct contact
with the pan. Heat is being transferred from the burner to the pan.
The bowl and the spoon are in direct contact with the hot soup. The heat flows
from the hot soup to the bowl and spoon.
The boy is roasting marshmallows over a fire using a metal rod. The rod
begins to get warm, as the thermal energy (heat) from the fire is being
transferred to the rod. The rod is in direct contact with the fire.
3. CONVECTION:
Convection is the movement of heat by a liquid, such as water or
through a gas – such as air.
The liquid or gas moves from one location to another carrying heat
along with it.
In convection, the heat source DOES NOT touch the objects being
heated.
Examples of convection:
 Convection is the reason that macaroni rises and falls in a pot of
heated water. Convection occurs in the heated water. The warm
water brings some of the macaroni up, and the cool water brings
some of the macaroni down. Heat is circulated through the water.
 This happens because the hot water is less dense than the
cool water that is at the top. The cool water at the top
then sinks since it is denser. This movement creates
convection current (like a cycle).
 Convection is also involved in a hot air balloon. The balloon
rises in the air because the hot air in the balloon is less dense
than the air around it. To lower a hot air balloon that is in the
sky, it would be necessary to turn down the burner in the
balloon. This would slowly cool the air inside the balloon. The
cool air is more dense. As the air inside the balloon cools, it
sinks and gently brings down the balloon.