P1 Physics- Energy Transfer by Heating Part 1
- Created by: chantellehoworth
- Created on: 18-02-16 15:16
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- Energy Transfer by Heating
- Infrared Radiation
- Part of the electro- magnetic spectrum
- Involves waves instead of particles
- We can detect infrared radiation with our skin- it makes us feel warm
- All objects EMIT infrared radiation
- The hotter it is, the more infrared radiation it emits in a given time
- Infrared Radiation can travel through a vacuum
- This is how we get energy from the sun
- Surfaces and Radiation
- black, matt surfaces
- Good at absorbing Infrared Radiation
- Good at emitting Infrared Radiation
- light, shiny surfaces
- Bad at emitting infrared radiation
- Bad at absorbing infrared radiaition
- Good Reflectors of Infrared Radiation
- black, matt surfaces
- Part of the electro- magnetic spectrum
- States of Matter
- There are 3 states of matter, solid, liquid and gas
- Solid
- particles vibrate at fixed positions
- Have a fixed shape
- They cannot flow
- They cannot be compressed or squashed
- Liquid
- Particles are in contact with each other
- The particles can move about at random
- Gas
- Particles move about randomly
- Particles are further apart than a liquid and solid
- Gases can move quickly in any direction
- Gas has the most energy and solid has the least energy
- Conduction
- Occurs mainly in solids
- Most liquids and gases are poor conductors
- Conduction in a metal is mainly due to free electrons transferring energy inside the metal
- Non-metals are poor conductors because they don't contain free electrons
- Materials such as wool and fibreglass are good insulators because they contain trapped air.
- Convection
- Occurs in fluids- liquids and gases
- When a fluid is heated it expands
- The fluid becomes less dense and rises
- The warm fluid is replaced by cooler, denser fluid
- The resulting convection current transfers energy throughout the fluid
- The warm fluid is replaced by cooler, denser fluid
- The fluid becomes less dense and rises
- Evaporation
- When a fluid turns into a gas
- The most energetic liquid molecules escape the surface and enter the air
- Therefore the temperature decreases
- Evaporation causes cooling
- Rate of Evaporation
- Increased by increasing the surface area of the liquid
- Increased by increasing the temperature of the liquid
- increased by creating a draught of air across the liquids surface
- Condensation
- When gas turns into a liquid
- often takes place on cold surfaces such as windows and mirrors
- Rate of Condensation is increased by...
- inreasing the surface area
- reducing the surface temperature
- Infrared Radiation
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