Conduction is the transfer of heat through direct contact of particles in solids, with good conductors like metals allowing easy transfer while insulators impede it. Convection transfers heat in liquids and gases through the movement of currents caused by less dense warmer particles rising and denser cooler particles sinking. Radiation transfers heat via electromagnetic waves without contact between the source and substance, as occurs in a greenhouse where solar radiation warms plants which then emit radiation.

2. Conduction
The kinetic energy of
the particles increases.
particles of a solid
This is the transfer of heat
in most solids.
Heat is transferred
by direct contact.

3. Conductors and insulators
metal
Insulators do not allow
heat to move through
them easily. plastic Double-glazed window
air
air space
cork
Conductors allow heat to
move through them
easily.

4. Convection
gas particles
liquid particles
convection currents
This is the transfer of heat in
liquids and gases.
Heat is transferred
by the movement
of currents.

5. Greenhouse
Radiation
solar
radiation
radiation
emitted by
plants
This is the transfer of heat by electromagnetic waves.
No contact is
necessary between
the source and the
heated substance.