The name we give to the range of radiation from radio waves to gamma rays
Electromagnetic spectrum
What we call the process of giving off radiation
Emission
What type of surfaces reflect radiation the best?
Shiny
What is the change of state from liquid to gas?
Evaporation
Which state of matter fits the container shape (but doesn't fill it)?
Liquid
What type of materials make the best thermal conductors?
Metals
Which two states of matter are fluids?
Liquids and gases
Why do hot fluids rise?
Heating causes them to expand so they become less dense and so rise
Name 3 greenhouse gases
Water vapour,
methane,
carbon dioxide
What type of surfaces are the best emitters of radiation?
Dark coloured / rough
What are the 3 common states of matter?
solids
liquids
gases
What is the change of state from solid to liquid?
Melting
What is the change of state from gas to liquid?
Condensation
Why are metals good conductors of heat?
They have free electrons that are free to move, can collide with each other, and pass on their energy.
What is convection?
The circulation of a fluid caused by warmer fluids rising and colder fluids falling.
Does evaporation warm things up or cool them down?
Cools them down
The type of radiation emitted by all warm things
Infrared
What type of surfaces absorb the most radiation?
Dark coloured (and rough)
Which state of matter has the lowest density?
Gas
What is the change of state from solid to gas?
Sublimation
What do we call something that is a poor conductor of thermal energy?
Insulator
What do we call the process of particles spreading out from an area of high concentration to a lower concentration?
Diffusion
Why does convection not happen in solids?
The particles in solids are not free to move around
Name 3 ways to speed up the rate of evaporation
increase the surface area,
increase the temperature,
increase the air flow
Name five methods of heat transfer
conduction,
convection,
radiation,
evaporation,
condensation
In the equation,
what does represent?
The specific heat capacity of the material
What does the U-value of a material tell you?
How good an insulator the material is
Why does good double glazing have a vacuum between the two panes of glass?
Vacuums do not contain air particles so reduce energy loss through convection and conduction
Which heat transfer mechanism works in a vacuum?
Radiation
Is air a good or bad insulator?
Good, (because it is a gas the particles are far apart)
If air is such a good insulator, why is cavity wall insulation more effective than just air?
Cavity wall insulation traps air so reduces convection as well as conduction
What is wrong with saying that heat rises?
It is the hot fluid (carrying the thermal energy) that rises, not the heat
Will a large difference in temperature between an object & its surroundings make its temperature change faster or slower?
Faster
In the equation,
what does represent?
The temperature change
Does a good thermal insulator have a low or high U-value?
Low
What is payback time?
The time it takes to save the amount of money it cost to install something (like solar panels). (After this time you are saving more than in cost to install the thing)
Which is the only heat transfer mechanism that uses electromagnetic (EM) waves?
Radiation
What type of materials contain free electrons?
Metals
Does a large block of copper need more or less energy to heat up by 5oC than a small block of copper?
More
Remember that
What is loft insulation usually made out of?
Fibreglass
What is the unit of energy (name and symbol)?
Joule (J)
Water has a high specific heat capacity. What does this mean?
It takes a lot of energy to increase its temperature
Remember
Name 5 ways of reducing energy loss from houses
loft insulation,
double-glazing,
cavity wall insulation,
draught proofing,
aluminium foil behind radiators
Which heat transfer mechanism relies on particles passing energy from one to the other
Conduction
Why are car radiators painted matt black?
Dark dull surfaces emit more heat energy than shiny light ones
Why are solar heating panels usually painted black?
Dark colours absorb more heat radiation than light ones so will be more efficient
Name 2 ways of speeding up condensation on a surface
increase surface area,
reduce temperature
At what temperature does water evaporate?
All temperatures above freezing. (The higher the temperature the faster it evaporates)