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Description
Flashcards by nadine pownall, updated more than 1 year ago
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Created by nadine pownall
almost 8 years ago
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| Question | Answer |
| How does the temperature of an object affect the rate at which it emits infrared radiation ? | The hight the temperature of the object, the greater the rate at which it emits infrared radiation. |
| What is a vacuum ? | A vacuum is a region that doesn't contain anything, even gas particles. |
| Why are houses in hot countries often painted white ? | Houses in hot countries are often painted white as white is the worst absorber of infrared radiation. |
| Why are the pipes at the back of a fridge often painted black ? | The pipes at the back of a fridge is often painted black as black is the best emitter of infrared radiation. |
| How is the arrangement of the particles in a liquid different from that in a solid ? | The particles in a liquid are in contact with each other but are not held together in fixed positions like those in a solid. |
| How is the arrangement of the particles in a gas different from that in a liquid ? | The particles in a gas are much more further apart and move alot more faster than those in a liquid. |
| Why are saucepans often made of metal with wooden handles ? | The metal base of a saucepan is a good conductor of heat, so heat is conducted quickly to the food in the pan. The wooden handle is a poor conductor, and so prevents any one picking it up from getting burnt. |
| Why are materials that trap air good insulators ? | Air is a poor conductor, so materials that trap air are good insulators. |
| Why doesn't convection occur in solids ? | Convection doesn't occur in solids as the particles are held together in fixed positions and so are not able to flow. |
| Why does a fluid become less dense when it is heated ? | A fluid becomes less dense when it is heated, because it expands, so there is the same mass of material in a larger volume. |
| What effect would decreasing the surface area of a liquid have on the rate of evaporation ? | Decreasing the surface area of a liquid would decrease the rate of evaporation. |
| What effect would decreasing the surface area of a liquid have on its rate of condensation ? | Decreasing the surface area would decrease the rate of condensation. |
| Why does painting an object dull black maximise the rate of energy transfer ? | Painting an object dull black maximises the rate of energy transfer, because dull black surfaces are the best emitters of radiation. |
| Why does trapping air in small pockets minimise the rate of energy transfer ? | Trapping air in small pockets will minimise the rate of energy transfer because convection currents cannot be set up. |
| The specific heat capacity of oil is 2100 J/kg degrees C. How much energy is needed to raise the temperature of 1 kg of oil by 1 degrees C ? | The energy needed is 2100 J. |
| The specific heat capacity of water is 4200 J/kj degrees C. How much energy is needed to raise the temperature of 2kg of water by 1 degrees C ? | The energy needed is 8400 J. |
| Why is fibreglass a good insulator ? | Fibreglass is a good insulator because it contains trapped air. |
| Why are the pipes that contain the water in a solar heating panel often painted black ? | The pipes that contain the water in a solar heating panel are often painted black because black is the best absorber of radiation. |
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