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Heat Transfer in Insulators
Name: Max
Status: student
Grade: 6-8
Location: MD
Country: USA
Date: Winter 2009-2010
Question:
Why do insulators prevent the transfer of heat?
Replies:
Hi Max,
Remember that there are at least three ways in which heat can be
transferred: conduction, convection, and radiation. When particles
transfer kinetic energy by coming into contact with each other, the
faster moving particle slows down and the slower particle moves
faster, we call this process conduction. When faster moving
particles migrate to areas where there are slower moving particles
so that the average speed in the slow area increases, we call this
convection. When heat is transferred through empty space by an
object that is giving of energy in the form of waves (light), we
call this radiation.
So, when an object is said to be an insulator, it is somehow able to
stop one or more of these transfers of heat. A vacuum, or low
pressure gas, is particularly good at limiting conduction because
there are few particles that come into contact. A shiny surface does
not allow light to penetrate into an object so it is particularly
good at stopping radiation transfer. A solid object that does not
flow or move so much at a molecular level may be good at stopping
convections. So you can imagine that a vacuum inside a container
that has a mirrored surface (such as what is inside those bottles
that often hold hot liquids, like the thermos brand) are
particularly good at being insulators since they tend to limit all
forms of heat transfer.
Greg (Roberto Gregorius)
Canisius College
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Update: June 2012
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