Zusammenfassung der Ressource
Physics 1a - Energy
- Heat Radiation
- Transferred by Infrared Radiation(IR)
- Emitted by solids, liquid and gases
- Any object can absorb or emit IR
- Bigger difference between the object and surrounding
- Faster Heat transfer
- Emitted from surface
- Can feel IR up close
- Dark, matt surfaces absorb better
- Than shiny, silver surfaces
- Kinetic Theory
- Three states of matter
- Solid
- Strong forces hold particles close together
- Not much energy
- Liquid
- Weaker forces of attraction
- Particles move at low speeds
- Gas
- Hardly any forces of attraction
- Lots of energy
- Give a state of matter more energy....
- Solids melt
- Liquids boil
- Conduction of Heat
- factors affecting rate of heat transfer
- surface area
- Mass
- type of material
- contact with conductor or insulator
- Free electrons in metals
- Smaller gaps between particles = conducts better
- Better if denser
- Convection
- Liquids and gases only
- Solid particles can't move so no convection
- Energetic particals move from hotter region to colder region
- The radiator uses convection
- Condensation and Evapouration
- Condensation is gas to liquid
- Particles slow down
- In contact with cold surfaces
- Steam on a mirror
- Evapouration is liquid to gas
- Particles gain heat energy
- Particles have to have enough energy to escape
- Energy efficiency in the home
- Cavity wall insulation
- Loft insulation
- Draught-proofing
- Hot water tank jacket
- thick curtains
- Specific Heat Capacity
- Amount of energy stuff can store
- Energy = mass x SHC x temp change
- units - J/kgdegreesC
- Heaters have high heat capacity to store loads of energy
- Energy Transfer
- Energy can be transferred usefully from one form to another, stored or dissipated - but can never be created or destroyed
- Efficiency of machines
- Sankey Diagram
- Cost of Electricity
- Choosing Electrical Appliances