Energy Transfer By Heating
- Created by: BThorogood
- Created on: 12-03-14 09:13
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- Energy Transfer by Heating
- Infrared Radiation
- The hotter and object is, the more infrared radiation it gives out in a given time.
- Infrared radiation is a type of electromagnetic radiation that comes from the Sun.
- All objects emit infrared radiation.
- Surfaces and Radiation
- Dark, matt surfaces emit more infrared radiation than light, shiny surfaces.
- Dark, matt surfaces absorb more infrared raditation than light, shiny surfaces.
- Light, shiny surfaces reflect more infrared raditation than dark, matt surfaces.
- States of Matter
- Flow, shape, volume and density are the properties used to describe each state of matter.
- The particles in a solid are held next to each other in fixed positions.
- The particles in a liquid move about at random, and are in contact with each other.
- The particles in a gas move about randomly, and are much further apart than particles in a solid or liquid.
- Conduction
- Metals are the best conductors of energy.
- Materials, such as fibre glass and wool, are the best insulators/
- Conduction of energy in a metal is due to, mainly, free electrons transferring energy inside the metal.
- Non-metals are poor conductirs because they do not contain free electrons.
- Convection
- Convection is the circulation of a fluid, caused by it being heated.
- Convection takes place in liquids and gases only.
- Heating a liquid or a gas makes it less dense, so it rises and causes circulation.
- Evaporation and Condensation
- Evaporation is when a liquid turns into a gas.
- Condensation is when a gas turns into a liquid.
- Cooling by evaporation can be increased by increasing the surface area of the liquid, the liquid's temperature, or by passing a breeze across the liquid's surface.
- Condensation on a surface can be increased by increasing the surface area, or by reducing the temperature.
- Specific Heat Capacity
- The greater the mass of an object, the more slowly its temperature increases when it is heated.
- Storage heaters use off-peak electricity to store energy in bricks.
- The rate of temperature change of a substance when it is heated depends on:
- The energy supplies to it.
- Its mass.
- Its specific heat capacity.
- Heating and Insulating Buildings
- U-values tell us how much energy per second passes through different materials.
- Solar heating panels use fuel to heat water, but they are expensive to buy and install.
- Energy transfer from our homes can be reduced by fitting:
- Loft insulation.
- Cavity wall insulation.
- Double glazing.
- Infrared Radiation
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