What
is Heat?
All
matter is made up of molecules and atoms. These atoms are always
in different types of motion (translation, rotational, vibrational).
The motion of atoms and molecules creates heat or thermal energy.
All matter has this thermal energy. The more motion the atoms or
molecules have the more heat or thermal energy they will have.
How
is heat transferred?
Heat
can travel from one place to another in three ways: Conduction,
Convection and Radiation. Both conduction and convection require
matter to transfer heat.
If
there is a temperature difference between two systems heat will
always find a way to transfer from the higher to lower system.
CONDUCTION--
Conduction
is the transfer of heat between substances that are in direct contact
with each other. The better the conductor, the more rapidly heat
will be transferred. Metal is a good conduction of heat. Conduction
occurs when a substance is heated, particles will gain more energy,
and vibrate more. These molecules then bump into nearby particles
and transfer some of their energy to them. This then continues and
passes the energy from the hot end down to the colder end of the
substance.
CONVECTION--
Thermal
energy is transferred from hot places to cold places by convection.
Convection occurs when warmer areas of a liquid or gas rise to cooler
areas in the liquid or gas. Cooler liquid or gas then takes the
place of the warmer areas which have risen higher. This results
in a continous circulation pattern. Water boiling in a pan is a
good example of these convection currents. Another good example
of convection is in the atmosphere. The earth's surface is warmed
by the sun, the warm air rises and cool air moves in.
RADIATION--
Radiation
is a method of heat transfer that does not rely upon any contact
between the heat source and the heated object as is the case with
conduction and convection. Heat can be transmitted though empty
space by thermal radiation often called infrared
radiation. This is a type electromagnetic
radiation . No mass is exchanged and no medium is required in
the process of radiation. Examples of radiation is the heat from
the sun, or heat released from the filament of a light bulb.
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