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