Section 2:
Transferring Thermal Energy
Chapter 6: Thermal Energy
WARM-UP:
 What does it mean to be a good
conductor?
 What types of materials are the
best conductors?
LEARNING GOALS
 Compare the transfer of heat energy
through conduction, convection, and
radiation.
 Compare and contrast conductors
and insulators.
 Explain how insulators are used to
control the transfer of thermal
energy.
TRANSFERRING
THERMAL ENERGY
 There are 3 ways that thermal
energy is transferred from place
to place:
 Conduction
 Convection
 Radiation
CONDUCTION
 Conduction: transfer of
thermal energy by collisions
between particles in matter
 Think of a metal spoon being
heated by a flame.
CONDUCTION
 Kinetic energy of the particles
close to the flame increases.
 Those particles collide with the
particles close to them and
thermal energy is transferred.
CONDUCTION
 Conduction occurs when
thermal energy is transferred
from place to place without
the transfer of matter!
HEAT CONDUCTORS
 Heat moves fastest by conduction
in solids.
HEAT CONDUCTORS
 Heat moves a little slower by
conduction in liquids.
HEAT CONDUCTORS
 Heat moves the slowest by conduction
in gases because the particles are so far
apart.
HEAT CONDUCTORS
 The best conductors of heat are
metals because their electrons flow
freely through the metal.
 Silver, copper, and aluminum are
among the best conductors of heat.
CONVECTION
 Convection: transfer of thermal
energy in a fluid (liquid or gas) by
the movement of warmer and
cooler fluid from place to place.
CONVECTION
 More energetic
particles collide with
less energetic
particles and transfer
thermal energy.
 More energetic
particles move faster
from place to place.
CONVECTION – THE LAVA
LAMP
 Oil is cool and dense and
sits on the bottom of the
lamp.
 As it warms, the oil
expands and becomes
less dense than the
surrounding fluid.
CONVECTION – THE LAVA
LAMP
 The oil then rises and
loses heat to the
surrounding fluid.
 It becomes dense again
and sinks.
RADIATION
 Radiation: transfer of energy by
electromagnetic waves
 Energy transferred by radiation is
called radiant energy.
RADIATION
 When you
stand near a fire
to warm your
hands, you are
warming them
using radiation.
INSULATORS
 Insulator: material that slows down
heat transfer
 Gases are usually much better
insulators than solids or liquids.
 Conduct heat poorly since
particles are far apart.
INSULATORS
Examples: fleece jacket and thermos
CHECK-IN:
 Would plastic foam (which contains
pockets of air) be a good insulator
or good conductor? Explain why.