# Energy Transfer By Heating

HideShow resource information
Convection occurs in which states?
Liquids and gases
1 of 25
When fluid is heated what happens to the density?
It decreases
2 of 25
What is a convection current?
Warm fluid becomes less dense and rises which is then replaced by cooler, denser fluid
3 of 25
What is convection?
Convection is the circulation of a fluid (liquid or gas) caused by heating it
4 of 25
What is evaporation?
Evaporation is when a liquid turns in to a gas
5 of 25
What is condensation?
Condensation is when a gas turns in to a liquid
6 of 25
What can increase the rate of condensation?
Increased surface area or reducing surface temperature
7 of 25
What can increase the rate of evaporation?
Increased surface area of liquid, increased temperature of the liquid, creating a draught of air across the liquid's surface
8 of 25
The rate of energy transfer to or from an object depends on what 3 things?
the shape size and type of material, materials which are in contact with the object, the temperature difference between the object and its surroundings
9 of 25
Three ways to maximise the rate of energy transfer to keep things cool?
Use things that are: good conductors, painted dull black, have maximum air flow around them
10 of 25
Three ways to minimise the rate of energy transfer to keep things warm?
Use things that are: good insulators, white and shiny, prevent convection currents by trapping air in small pockets
11 of 25
What is specific heat capacity?
Specific heat capacity of a substance is the amount of heat required to raise the temperature of 1kg of the substance by 1 degree celcius
12 of 25
If an object has a greater mass, will its temperate increase faster or slower?
Slower
13 of 25
What is the formula for specific heat capacity?
E = m x c x temp change
14 of 25
How can you reduce the rate of energy transfer in our homes?
Fibreglass loft insulation, cavity wall insulation, double glazing, draught proofing, aluminium foil behind radiators
15 of 25
What do U-Values tell us?
They tell us how much energy per second passes through different materials
16 of 25
If the U-Value of an object is higher is it a good or bad insulator?
The lower the value the better the insulator
17 of 25
Why are solar panels cheap to run?
They are cheap to run because they require no fuel to heat the water - only the suns energy
18 of 25
What are disadvantages of solar panels?
Only work in the daytime, expensive to buy and install
19 of 25
Which type of energy transfer is by electromagnetic waves?
20 of 25
What prodperties of surfaces make them good absorbers of infra red radiation?
Dark, matt surfaces
21 of 25
What properties of surfaces make them bad absorbers of infra red radiation?
Light, shiny surfaces
22 of 25
Which materials are the best conductors?
Metals
23 of 25
Why are materials such as wool and fibreglass poor conductors?
They contain air pockets which traps air and reduces the number of collisions between particles transferring energy
24 of 25
Why are metals good conductors?
They are good because they have lots of free electrons which when heated gain kinetic energy and move through the metal
25 of 25

## Other cards in this set

### Card 2

#### Front

When fluid is heated what happens to the density?

It decreases

### Card 3

#### Front

What is a convection current?

### Card 4

#### Front

What is convection?

### Card 5

#### Front

What is evaporation?