Thermal Processes

Question 1

what are thermal conductors?

Answer 1

materials that allow thermal energy to transfer through them quickly

Question 2

how does conduction happen in a metal?

Answer 2

if one end of a conductor is heated, the atoms begin to vibrate more vigorously. as the atoms in a solid are linked together by chemical bonds, they can pass on the vibrations.

metals are particularly good at this because they have delocalised electrons that can transfer the kinetic energy to other electrons in the metal.

Question 3

why are gases and liquids such poor conductors?

Answer 3

• particles are far apart
• bonds are weak (liquids)
• no delocalised electrons

Question 4

why is a vacuum a perfect insulator?

Answer 4

a vacuum does not contain any particles so it cannot pass on any kinetic energy

Question 5

how does a convection current in a liquid occur?

Answer 5

when a fluid is heated, energy is transferred to the particles, causing them to move faster and further apart. this makes the heated fluid less dense than the unheated fluid, so the less dense, warmer fluid rises above the colder one, causing the fluids to circulate in a convection current

Question 6

dull black surfaces are:

Answer 6

• good emitters of radiation

- good absorbers of radiation

Question 7

bright shiny surfaces are:

Answer 7

• poor emitters

- good absorbers