What is convection?
When hot air rises because of its lower density. Only convection in gas and water
What is conduction?
Conduction is when heat is moved through an object the particles start to vibrate faster as the energy is transferred
What does thermal mean?
Heat/heat energy
What does thermal conductivity of materials mean?
Thermal conductivity of a material refers to the rate at which it transfers heat. The more thermally conductive it is the greater the rate at which it will transfer heat energy.
What is insulation?
Insulation means to reduce the amount of energy transfer across a material
What are some materials which are good thermal insulators?
Polystyrene
Fibreglass
Cardboard
What is infrared radiation?
Infrared radiation is a type of electromagnetic wave which transfers heat energy
Thermal heat energy is emitted from objects as infrared radiation
What is a black body?
A perfect black body is an object that absorbs all of the radiation that hits it.
A black body does not reflect or transmit any radiation
What is black body radiation?
Radiation emitted by a perfect black body
What type of materials are better absorbers?
Dull matt dark surfaces are better absorbers of infrared radiation than shiny light surfaces
What types of materials are best for emitting infrared radiation?
Dull matt dark surfaces are better emitters of infrared radiation than shiny light surfaces
What is specific heat capacity?
Specific heat capacity is a property of a material that determines how much energy is required to raise the temperature of 1kg of the material by 1 degree celcius
What three factors do you need to consider when calculating the amount of heat needed to raise the temperature?
Conductivity
The mass
The change in temperature
What is the equation for energy?
Energy = mass x specific heat capacity x change in temperaure
What is an insulator? how does it work?
Insulators are poor conductors of heat so this means that the heat is not easily transferred away. An insulator does not transfer heat very well which means it stays where it is for longer
What are double glazed windows?
These windows have air or a vacuum between two panes of glass. If the double glazing has a vacuum there will be no conduction or convection.
If the double glazing has air between the glass then the convection is reduced as the air has little room to move air is a very poor conductor so there will be very little heat loss by conduction
What are cavity walls and loft insulation?
Insulating materials are bad conductors and so this reduces the heat loss by conduction. The material also prevents air circulating inside the cavity therefore reducing heat loss by convection
What is a u-value?
Measures the rate of heat transfer through a building element (walls, roofs,floors)
A wall with a high u-value will transfer more heat so the room would lose heat energy quicker
