P1- Conduction, Convection & Radiation
- Created by: webbie1310
- Created on: 08-02-16 18:45
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- P1
- Transfer Of Energy
- Air is a good insulator, as the particles are far apart.
- If air is trapped in a material, the material will be an insulator.
- Heat energy doesn't stay in one place; it moves around. Hot air rises & cooler air replaces it.
- Kettles made of metal have shiny surfaces to reduce heat loss by radiation.
- Hot-water tanks are made of stainless steel & also have shiny outer layer to reduce heat loss by radiation. They usually have an insulating jacket to reduce heat loss by conduction & convection
- Air is a good insulator, as the particles are far apart.
- Radiation
- Hot objects emit mainly infra-red radiation, which can pass through a vacuum i.e no medium is needed for its transfer.
- The amount of radiation given out or taken in by an object depends on its surface.
- Dark matt surfaces emit more radiation than light shiny surfaces as the same temperature.
- Dark matt surfaces are better absorbers (poorer reflectors), of radiation than light shiny surfaces at the same temperature.
- Dark matt surfaces emit more radiation than light shiny surfaces as the same temperature.
- Conduction.
- Transfer of heat energy through a substance from a hotter region to a cooler region without any movement of the substance itself.
- As a substance i.e a metal poker, is heated the kinetic energy is transferred between the particles & the energy is transferred along the substance.
- Metals have free electrons which can move through the material carrying energy. This makes metals a very good conductor.
- Convection
- Transfer of heat energy from hotter regions to cooler regions by the movement of particles.
- As a liquid or gas gets hotter, its particles move faster, causing it to expand & become less dense.
- The particles in the hotter region will rise up & be replaced by particles from colder, denser region.
- Air warms up, becomes less dense & rises
- Air. calls, becomes more dense & sinks.
- Cooler air replaces air which has risen.
- Air. calls, becomes more dense & sinks.
- Transfer Of Energy
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