HEAT TRANSFER

HEAT TRANSFER
Key notes:
1. In poor conductors, heat is transferred solely by the vibrations of particles.
2. In metals, more energetic free electrons from the hot end moving to the cold
end help to transfer heat energy faster from one end to the other.
3. Conduction is the transfer of heat through a material medium by the vibrations
of the particles in the medium.
4. Metals are good conductors of heat.
5. Non-metals, liquids and gases are poor conductors of heat.
6. Convection is the main mode of heat transfer in fluids.
7. Convection occurs when the warmer part of the fluid moves up while the
cooler part sinks down. The warmer part of the fluid has a lower density than
the cooler part.
8. Streams of warm moving fluids are called convection currents.
9. Heat is circulated around the fluid by convection current until the temperature
throughout the fluid has become the same.
10. Radiation is a process of heat transfer that does not require a material medium.
Heat is transmitted in the form of electromagnetic waves.
11. A dull black surface is both a good emitter and a good absorber of radiant
energy.
12. A shiny polished surface is both a poor emitter and a poor absorber of radiant
energy.