Download Chapter 6.2 Notes

6.2 Notes – Transferring Thermal Energy
Conduction- transfer of thermal energy through matter by the direct contact of particles.
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Particles bang into each other transferring the thermal energy.
Thermal energy can be transferred by conduction from one material to another
or through a material.
Heat conductors- occurs in solids, liquid, and gasses.
o Solids are the best conductors
o Good solid conductors are metals – silver, aluminum, and copper
o Poor solid conductors are wood, plastic, and fiberglass.
Convection- transfer of energy by motion of the heated particles in a fluid.
Fluids are liquids and gasses.
Occurs by a convection current:
1. You have a particle by a heat source, as the particle heats up, it becomes less
dense (heavy) and rises.
2. The rising particle then cools off and becomes more dense and starts to sink.
3. The sinking dense particle will then move towards the heat source to start the
cycle over again.
Radiation- Transfer of thermal energy by electromagnetic waves. Comes from the
sun or any form of light.
*Also called Radiant energy.
-Radiation goes through solids and liquids that are clear the best.
-Can go through empty space where there are no particles. (happens in outer space
and in a vacuum)
*Light colors reflect radiant energy
*Dark colors absorb radiant energy
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Gasses absorb less radiant energy and transmit more radiant energy because
particles aren’t as close together.
Controlling Heat Flow:
Insulators- a material that doesn’t allow heat to flow through it easily.
-Poor Insulators are metals
-Good Insulators are wood, plastic, and fiberglass.
-Gasses are better insulators than solids or liquids because they don’t conduct heat
well and keep convection currents flowing in it.
- Use insulation foam to insulate buildings because they create more air
pockets.
- Measure Insulation in R -value, which stands for the resistance of heat flow.
- The smaller the R-value of insulation the better it allows heat to flow through
it, so it is not as good of an insulator.
Thermos- The following picture describes how a thermos works with transferring thermal
energy.