Energy Transfer by Heating
- Created by: JessicaGrey
- Created on: 17-04-16 14:26
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- Energy Transfer by Heating
- Infrared Radiation "heat"
- No particles!!!
- All objects emit and absorb radiation
- Can be detected with skin by not eyes
- Matt black surfaces= best emitters and absorbers
- Shiny white surfaces= poor emitters and absorbers. Good reflectors
- Kinetic Theory
- Solids; particles are very close together, they vibrate around each other
- Fixed shape
- Fixed volume
- Liquids; particles close together but can move around
- Fixed volume
- Takes shape of container
- Gases; particles are very far apart, they move quickly and randomly
- Fills space avaliable
- Solids; particles are very close together, they vibrate around each other
- Conduction
- Metals are very good conductors- atoms arranged neatly and delocalised electrons
- Poor conductors= insulators
- eg, wood, air, polystyrene and plastic
- Convection- liquids and gases
- When heated particles gain kinetic energy/ vibrate
- Liquid then expands- becomes less dense
- The liquid rises as it is lighter
- Cools and condenses- becomes more dense
- Liquid falls
- Cools and condenses- becomes more dense
- The liquid rises as it is lighter
- Liquid then expands- becomes less dense
- When heated particles gain kinetic energy/ vibrate
- Evapouration
- Some particles with enough energy escape from the surface of the water. Remaining liquid is cooler
- To increase rate of evap; increase surface area, increase water temperature, wind/ fan/ draft
- Condensation
- Particles lose heat/kinetic energy. they move slower and closer together. gas condenses to a liquid
- To increase rate of condensation; increase surface area
- U-Values- rate of heat transfer through a material
- High U-value = lots of heat transfer- bad
- Low U-value = little heat transfer- good
- Specific Heat Capacity
- Energy required to change the temperature of one kilogram of the substance by one degree Celsius
- Formula given
- Infrared Radiation "heat"
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