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Description
Flashcards by tarank2001, updated more than 1 year ago
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Created by tarank2001
about 10 years ago
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| Question | Answer |
| What is infared radiation? | Infared radiation is an electromagnetic wave like light, it is the transfer of energy by electromagnetic waves. Every single object emits Infared radiation. The hotter an object is the more Infared radiation they emit. |
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What are the states of matter? What properties do they have?
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swag_2 (image/jpg)
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A substance can change state from one to another.
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StateChanges.gif (image/gif)
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| More of Infared Radiation... | All objects emit and absorb thermal radiation, which is also called infrared radiation. Infrared radiation is a type of electromagnetic radiation, which involves waves rather than particles. This means that, unlike conduction and convection, radiation can even pass through a vacuum. |
| What is conduction? | Conduction is the transfer of heat through as solid. The kinetic energy is passed from particles to particles in a solid. Metals are good conductors because they have free electrons that carry kinetic energy. However, non-metals rely on atomic vibration. |
| Why are metals good conductors? | Metals are good conductors because they have free electrons. As metal heats up, the kinetic energy of free electrons increases. the free electrons collide with the other particles and heats them up. Free electrons pass on kinetic energy onto other ions, so the whole metal heats up. |
| What are insulators? | Insulators are substances which do not readily allow the passage of heat or sound. Most good insulators have trapped air in them. Examples include... plastic, wood, and air. |
| What is convection? | Convection only happens in gases and liquids (fluids). The hot gas above a heat source, heats up, becomes less dense and rise. Then it has cools down, condense and falls back down. This is therefore a convection current. |
| What is evaporation? What is condensation? | Condensation is when a gas particle changes (cools down) to a liquid particles e.g. steam turns into water vapour Evaporation is when a liquid turns into a gas e.g. a puddle in the sun |
| How do you increase the rate of evaporation? | Higher temperature More ventilation Leave a larger surface area coverage low levels of humidity |
| Explain the cooling effect of evaporation? | There are weak attractive forces that exist between the molecules. Faster molecules with higher kinetic energy break the force of attraction and leave the liquid by evaporation. The liquid is now cooler because the average kinetic energy of the remaining molecules is lower |
| Dependency on things for energy transfer? | The rate of energy transferred to or from an object depends on: the shape, size, material type the type of material it is in contact with the temp difference between the object and it's surroundings. |
| Specific Heat Capacity - What is it? | the SHC is... the energy transferred to 1kg of a substance to raise it's temperature by 1 Celsius. It can be calculated using: E = M x C x (circle with a line) Supplied energy = mass of substance x SHC x Temperature difference |
| How to insulate your house? Give examples... | Loft insulation (Fibre Glass) Aluminium Foil (reflects radiation away from the wall) Cavity wall insulation (reduces heat loss through walls) Double-glazed windows (reduce convection -vacuum) |
| U-values and payback time? What are they? | U-values are.. a measure of heat loss, the lower the u-value the better insulator it is. The payback time is the cost of the insulation/annual fuel savings |
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