Energy Transfer

Question 1

All objects do what with infra-red radiation?

Answer 1

Emit it and absorb it.

Question 2

Increasing and object’s temperature increases what?

Answer 2

The amount of infra-red radiation it emits.

Question 3

Dark, matt surfaces are good…

Answer 3

…absorbers and good emitters of infra-red radiation.

Question 4

Light, shiny surfaces are poor…

Answer 4

…absorbers and poor emitters of infra-red radiation, but they are good reflectors of infra-red radiation.

Question 5

Kinetic theory states that…

Answer 5

…particles of solids, liquids and gases have different amounts of energy.

Question 6

Free electrons allow a metal to be a good what?

Answer 6

Conductor.

Question 7

Conduction usually occurs in what?

Answer 7

Solids.

Question 8

Convection occurs in what?

Answer 8

Fluids (liquids and gases).

Question 9

The bigger the temperature difference with the surroundings…

Answer 9

…the faster the rate at which energy is transferred to the surroundings as heat.

Question 10

Factors that effect the rate of heat transfer:

Answer 10

Surface area and volume.
Material from which the object is made.
The nature of the surface with which the object is in contact.

Question 11

U-value is a measure of what?

Answer 11

The rate at which a material transfers heat (how good of an insulator it is).

Question 12

The lower the U-value…

Answer 12

…the better the insulator.

Question 13

Solar panels may contain water. What does the sun’s radiation do to this water?

Answer 13

It heats it to either provide hot water for the house or heat the building.

Question 14

Specific heat capacity means what?

Answer 14

The amount of energy required to heat a kg of an object by 1C.

Question 15

Specific heat capacity is measured in what unit?

Answer 15

J/kgC (Joules per kilogram degree celsius).

Question 16

Specific heat capacity formula:

Answer 16

E = m x c x theta

m = mass in kg
c = specific heat capacity in J/kgC
theta = temperature change in Celsius