Presentation for teaching heat energy to middle schoolers

1. Heat Energy

2. What is Heat Energy?
• Heat is a form of energy that is transferred from one object/region to
another, as a result of the temperature difference between them. This
energy transfer is always from a hotter region to a cooler region.
• Thermal energy is the energy possessed by a body due to its
temperature.
• Temperature is a measure of how hot or cold a body is. Specifically, it
is a measure of the average kinetic energy of the particles in an object

3. What is Heat Energy?
Hot region Cool region
Heat energy

4. Difference between heat and temperature.
Heat Temperature
Measured in Joules Measured in either Celsius , Fahrenheit or Kelvin
Form of energy that can be transferred from one
object to another
It is a measure of how hot or cold an object is.
It’s symbol is Q It’s symbol is T

5. Heat transfer happens in 3 ways:
•Conduction
•Convection
•Radiation
How is Heat Transferred?

6. How is Heat Transferred?
• Transfer of heat through solids.
• Materials that allow heat to be
transferred easily through them
are good conductors of heat, e.g.
copper, aluminium, mercury, etc.
Because of this, good conductors
are used to make products such
as cooking utensils,
heating/cooling coils for air
conditioners and heaters,
thermometers, etc.
• Bad conductors of heat are
referred to as insulators, e.g.
wood, plastic, feathers, wool, etc.
Conduction

7. Convection
• Transfer of heat energy in liquids
and gases (fluids).
• When a fluid gets hot it expands,
making the hotter region of the
fluid less dense than the cooler
region.
• The less dense hotter fluid moves
away from the heat source, and
the more dense cooler fluid
moves in to replace the hotter
fluid, creating a convection
current
How is Heat Transferred?
Hotter fluid
Cooler fluid

8. Ventilation in a building
warm air out warm air out
cold air in

9. Radiation
• It is the transfer of heat energy
directly through space or a
vacuum.
• Heat from radiation, also called
radiant heat, can travel between
two objects without heating the
space in between. This because
radiant heat is transmitted as a
wave.
• Examples of heat transfer by
radiation include the sun heating
the earth (solar radiation), heat
from a fire warming people on a
cold day, space heaters used for
heating cold rooms, etc.
How is Heat Transferred?

10. Vacuum Flask
It is used to keep hot substances hot and cold substances cold, it does
this by preventing the various ways by which heat is transferred from
occurring.
It is a doubled-walled glass vessel. The outer surface of the inner wall
and the inner surface of the outer wall are silvered. The space between
them creates a vacuum and the two walls are sealed at the top. The
flask is placed on a cork in a metal case and is secured at the neck with
a ring of rubber. Heat from a hot liquid cannot escape via conduction or
convection because of the vacuum created between the walls and also,
the outer surface of the inner wall and the inner surface of the outer
being silvered prevents heat loss by radiation as silver is a bad radiator
of heat.