Transfer of thermal energy by the vibration of particles
Convection
Transfer of thermal energy when particles in a heated fluid rise
Convection current
The movement of heated fluids where hot fluid moves upwards, and cold fluid moves downwards
Infrared radiation
Radiation given off by the Sun and other objects that brings about energy transfer
Radiation
The transfer of energy as a wave
Temperature
A measure of the motion and energy of particles
Thermal conductor
Material that allows heat to move quickly through it
Thermal energy store
The store containing energy due to the vibration or movement of particles of a substance
Thermal imaging camera
A camera that absorbs infrared and produces a (false colour) image
Thermal insulator
Material that only allows heat to travel slowly through it
Thermometer
Instrument used to measure temperature
Energy
Energy is needed to make things happen
Energy resource
Something with stored energy that can be released in a useful way
Fossil fuel
Non-renewable energy resources formed over millions of years from the remains of ancient plants or animals. Examples are coal, crude oil, and natural gas
Joule
The unit of energy, symbol J
Kilojoule
1 kilojoule = 1000 J, symbol kJ
Kilowatt
1 kilowatt = 1000 W, symbol kW
Kilowatt hour
The unit of energy used by electricity companies, symbol kWh
Non-renewable
An energy resource that cannot be replaced once used up and will run out, such as coal, oil, or gas
Power
How quickly energy is transferred by a device (watts)
Renewable
An energy resource that can be replaced and will not run out. E.g. solar, wind, waves, geothermal, and biomass
Watt
The unit of power, symbol W
The temperature of a substance is a measure of how hot or cold it is. Temperature is measured with a thermometer, it has the units of degrees Celsius (oC)
The thermal energy of a substance depends on the individual energy of all of the particles, it is measures in Joules (J)
As all particles are taken into account, a bath of water at 30 oC would have more thermal energy than a cup of tea at 90 oC as there are many more particles
The faster the particles are moving, the more thermal energy they will have
When particles are heated they begin to move more quickly
The energy needed to increase the temperature of a substance depends on: the mass of the substance, what material the substance is made of, how much you want to increase the temperature by
Conduction is the transfer of thermal energy by the vibration of particles, it cannot happen without particles
Every time particles collide they transfer thermal energy
Conduction happens effectively in solids as their particles are close together and can collide often as they vibrate around a fixed point
Metals are also good thermal conductors as they contain electrons which are free to move
In conduction the thermal energy will be transferred from an area which has a high thermal energy store (high temperature) to an area where there is a low thermal energy store (low temperature)
Gases and liquids are poor conductors as their particles are spread out and so do not collide often, we call these insulators
Convection is the transfer of thermal energy in a liquid or a gas, it cannot happen without particles
As the particles near the heat source are heated they spread out and become less dense, this means that they will rise
More dense particles will take their place at the bottom nearest the heat source creating a constant flow of particles
This is known as a convection current
Convection cannot happen in a solid as the particles cannot flow, they can only move around a fixed point
Radiation is a method of transferring energy without the need for particles