P1.1 - Energy Transfer by Heating
- Created by: alishamunson
- Created on: 25-02-17 18:58
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- P1.1 - Energy Transfer by Heating
- 1.1
- Infrared radiation is energy transfer by electromagne-tic waves.
- All objects emit infrared radiation.
- The hotter the object, the more infrared radiation it emits in a given time.
- 1.2
- Dark, matte surfaces emit radiation the quickest.
- Dark, matte surfaces absorb radiation the quickest.
- Light, shiny surfaces reflect the most infrared radiation.
- 1.3
- Particles in a solid are held next to each other, vibrating in their fixes positions.
- Particles in a liquid move about at random and are in contact with each other.
- Particles in a gas more about randomly and are farther apart than particles in other matters.
- Flow, shape, volume and density are properties used to describe each state of matter.
- Particles in a solid are held next to each other, vibrating in their fixes positions.
- 1.4
- Metals are the best conductors.
- Wool and fibreglass are good insulators.
- Conduction in a metal is mainly due to free electrons transferring energy inside the metal.
- Non-metals are poor conductors as they don't have free electrons.
- 1.5
- Convection takes place in a fluid.
- Convection is the circulation of a fluid caused by heating it.
- Heating a fluid makes it less dense so it rises and causes circulation.
- 1.7
- The rate at which energy is transferred depends on:
- Material the object is in contact with.
- Objects shape.
- Objects surface area.
- Objects shape.
- Material the object is in contact with.
- To maximise the rate of energy transfer to keep things cool:
- Make sure they're conductors.
- Paint them dull and black
- Have the air flow around them maximised.
- Paint them dull and black
- Make sure they're conductors.
- To minimise the rate of energy transfer to keep things warm:
- Make sure they're insulators.
- Make them white and shiny.
- Prevent convection currents by trapping air in small pockets.
- Make them white and shiny.
- Make sure they're insulators.
- The rate at which energy is transferred depends on:
- 1.6
- Evaporation is when a liquid turns into a gas.
- The rate of evaporation is increased by:
- Increasing the surface area.
- Increasing the temperature.
- Creating a draught of air across the liquid's surface.
- Increasing the temperature.
- Increasing the surface area.
- The rate of evaporation is increased by:
- Condensation is when a gas turns into a liquid.
- The rate of condensation is increased by:
- Increasing the surface area.
- Reducing the surface temperature.
- Increasing the surface area.
- The rate of condensation is increased by:
- Evaporation is when a liquid turns into a gas.
- 1.8
- The greater the mass, the more slowly its temperature increases when heated.
- Specific heat capacity: E = m x c x ?
- E = energy transferred, J
- M = mass, kg
- c = specific heat capacity, J/kg°C
- ? = temperature change, °C
- The rate of temperature change in a substance when heated depends on the energy transferred to it, its heat and its SHC.
- 1.9
- The rate of energy transfer to and from our homes can be reduced.
- Install insulators to reduce it.
- U-values tell us how much energy per second passes through different materials.
- The lower the U-value, the better the material is as an insulator.
- To minimise the rate of energy transfer out of houses you can:
- Fit double glazing.
- Fit fibreglass loft insulation.
- Fit cavity wall insulation.
- Fit draught proofing.
- The rate of energy transfer to and from our homes can be reduced.
- 1.1
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