P1.1 Flashcards
What are the 3 ways of transferring thermal energy?
Conduction, convection and radiation
What is infra-red radiation?
A type of electromagnetic radiation that uses waves instead of particles e.g. in space
Describe conduction
When energy is transferred from particle to particle, by colliding with each other
Describe convection
When particles with energy move around, to transfer energy to another space
Describe radiation
Energy travelling with waves instead of particles
What materials are good absorbers of infrared radiation?
Dark, matte surfaces
What surfaces are slow to emit infrared radiation?
Shiny, silver surfaces
What is kinetic theory?
Kinetic theory explains the physical properties of a thing, through its particle movement
How can you reduce the loss of heat through conduction?
Good insulators, vacuums
How can you reduce the loss of heat through convection?
Putting on a lid on something
How can you reduce the loss of heat through radiation?
Using silvered surfaces instead of dark, matt ones
What is Specific Heat Capacity?
The amount of energy required to raise the temperature of 1kg of a material by 1^os
What is the formula for SHC?
energy (m) = M(mass)C(SHC)(triangle)T (temperature change)
How do solar water heaters work?
Solar water heaters work by absorbing infrared radiation from the sun. The black pipes filled with running water absorb the radiation through conduction and heat the water, which flows back to the tank an passes the energy onto other particles using convection.
What do u values measure?
How effective a material is at insulating.
What factors affect the rate of thermal conduction?
The conductivity of the material, area of the material, thickness of the material and temperature difference across the material
What is a vacuum?
A space with no particles in it
What gives off infrared radiation?
The sun
What materials are good reflectors if infrared radiation?
Shiny, silver surfaces
Where does conduction occur?
Solids
Where does convection occur?
Liquids and gases
What is a poor conductor called?
An insulator
Why does a fluid become less dense when it is heated?
Because energy is transferred to the particles which results in them moving apart randomly. The fluid is now less dense than the solid it was earlier because there are less particles in a closed space.
What 3 things increase the rate of evaporation?
Air movement above the liquid
Temperature
Surface area of the liquid
What 2 things increase the rate of condensation?
Decrease in temperature
Surface area of the gas
