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Description
Flashcards by ManishaBhaker78, updated more than 1 year ago
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Created by ManishaBhaker78
over 8 years ago
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| Question | Answer |
| What are the three ways that heat is transferred | •conduction •convection •radiation |
| Describe conduction | •occurs mainly in solids •conduction of heat energy is when vibrating particles pass on their extra kinetic energy • to neighboring particles until the whole solid is heated |
| What does conduction work best in | •In denser solids because their particles are a lot closer (making the particles collide more) • BUT materials that have spaced out particles conduct heat slower [These are called insulators] |
| Why are metals good conductors? | •Because of their delocalised electrons • they can move more freely and transfer the heat quicker. |
| What is heat/ infrared radiation? | A former of heat that can be emitted by solids liquids and gases |
| Describe how texture and colour have a big influence on infrared radiation | •dark matt surfaces ABSORB infrared falling on them •BETTER than light, shiny surfaces (gloss white or silver) • light shiny surfaces REFLECT alot of I.R falling on them. (Eg - vacuum flask) |
| What can infrared only travel through | A vacuum I.e space (where there are no particles) |
| Where do covenection currents happen | Only in gasses and liquids |
| Explain a convection current in a liquid | • water gets heated • the particles gain kinetic energy and move faster • this means they become less dense • this causes the water to rise • and displace the less energetic particles • they then sink and the then gain energy and repeats • this is called a convection current |
| Use an example to show how heat transfer is limited in a device | • the glass bottle is double-walled to stop all conduction / convection currents through the sides • the walls either side of the vacuum are Silverdale to keep heat loss by radiation to a minimum. • the bottle is supported using insulating foam - this minimises heat conduction to or from the outerminal glass bottle. • the stopper is made of plastic and filled with cork(or foam) to reduce any heat conduction through it. |
| Describe the process of condensation | • when a gas cool, the particles in gas slow down and lose kinetic energy • the attractive forces between the particles pull them closer • if the temperature gets cold enough and the gas particles get close enough allowing CONDENSTATION to take place... • the gas turns to a liquid |
| What is evaporation? | When particles escape from a liquid into a gas |
| Describe the process of evaporation | • only particles at the surface of a liquid can EVAPORATE • BUT This will only happen if the particles : are travelling in the right direction to escape the liquid • if the particles have enough kinetic energy to overcome the attractive forces of the other particles |
| What are the factors of evaporation ( what happens to the liquid as particles evaporate) | • as the fastest particles evaporate, the remaining particles decreases • meaning the average temperature falls • this 'cooling effect' can be useful when your hot and sweating |
| How could you increase the rate of condensation and evaporation? | EVAPORATION • higher temp • lower density - forces between particles will be weaker • larger surface area • more airflow CONTESTATION • temperature of the gas is lower • temp of the surface the gas touches is low • higher density - strengthening the forces between the particles • airflow is less |
| Use an example to describe how heat transfer is limited in a device | Vacuum flask • the glass bottle is double-walled with a vacuum to stop all conduction and convection through the sides • the walls either side of the vacuum are silvered to minimise heat loss by radiation • the bottle is supported by insulating foam to minimise heat conduction to or from the outer glass bottle • the stopper is made of plastic and filled with cork or foam to reduce any heat conduction through it. |
| How do animals and humans control heat transfer? | -HUMANS • in the cold the hairs on your skin stand to trap a thicker layer of insulating air around your body • when your warm your body diverts more blood flow near the surface of your skin so that more heat can be losses by radiation. -ANIMALS • animals in hotter climates have larger ears than those that live in colder climates to controlled thir heat transfer |
| What is a u - value | U-values show how fast heat can transfer through a material So the better the insulater the lower the u-value |
| How do you work out the payback time? | Payback time (years)= cost of insulation(£) ÷ savings per year in fuel costs (£) |
| What is the difference between 'cost effectiveness' and 'effectiveness'? | • the most cost effective tend to be the cheapest - they have short payback times (good) • the most effective methods of insulation give you the biggest annual saving - so eventually the money you saved on heating bills will equal the initial cost of installing the insulation. |
| Name 9 types of energy | 1) electrical energy 2) light energy 3 sound energy 4) kinetic /movement energy 5) nuclear energy 6) thermol/heat energy 7) gravataional potential energy 8) elastic potential energy 9) chemical energy |
| What are kWh | Units of energy |
| Name 4 non renewable sources of energy and there rolls | • coal • oil • natural gas • nuclear fuels - all gonna run out - all do damage to the environment - provide us with most of our energy |
| Name 8 renewable sources of energy and there rolls | • wind • waves • tides • hydroelectric • solar • geothermal • food • biofules - never run out -they do damage but in less nasty ways - don't provide much energy as they are unreliable |
| Describe how energy sources can be burned to drive turbines in a power station and produce electricity | • the fossil fuel is burned • to convert is stored chemical energy into heat • the heat energy is used to heat water to produce steam • the steam turnshower the turbine • convertible get heat energy to kinetic energy • turbine is connected to a generator • which transfers kinetic energy to electrical energy |
| What is a nuclear reactor | A nuclear power station that uses nuclear fission of uranium and plutonium producing the heat to make the steam and turn the turbines • but it takes the longest to start up. |
| What are biofuels made out of and what is there use? | They are made of plants and waste • they also make electricity through the same method as fossil fuels would. • also used in some cars |
| How are non-renewables linked to the environmental problems | • fossil fuels (coal oil and gas) release co2 in the atmosphere when they're burned • adding to the greenhouse effect and global warming • burning coal releases sulfur dioxide which causes acid rain • coal mining makes a mess of landscapes • oil spillages effect mammals and birds that live around the sea • nuclear power create a lot of dangerous waste |
| What is the national grid? | It takes takes electrical energy from power stations to to where it's needed in homes and industry |
| Describe the rolls of the pylons and transformers when electricity is passed out | • to get 400000v to transmit power requires transformers as well as big pylons with huge insulators • the transfers have to step the voltage up at one end for efficient transmission • and then bring it back down to safety at the other end - basically the voltage is increased (stepped up) using a step up transformers - it's then reduced again ( stepped down) at the consumer end using stop down transformer |
| What are the differences between transverse and longitudinal waves | Transverse waves: • light and all other EM waves • looks like a slinky spring wiggling up and down Longitudinal waves: • sound waves and ultra sound waves • a slinky spring when push one end ( it compresses ) |
| What is the law of reflection? | The angle of incidence always equals the angle of reflection |
| What is the definition of diffraction | Waves spreading out, which changes depending on how big the Gap is |
| What is the definition of refraction | When you change the speed of a wave it can change its direction Whether it's in air or glass. |
| sing the electromagnetic wave song | Radio waves - low freq microwaves Infrared radiation Visible light ultra violet X - RAYS Gamma rays - high freq |
| What proves that the universe is expanding | red shift |
| What is red shift | • when we look at distant galaxies we can see the same patterns but at slightly lower frequencies then they should be • they're shifted toward the red end of the spectrum If a galaxy is red shift it is moving away very quickly |
| What is the doppler effect? | • when something that emits waves moves towards you or away from you • the frequency of the waves seems different • *compared to when it was stationary * |
| Describe what happens to the wavelength and frequency as a race car is moving towards and when it moves away from you..... | • the frequency of it moving towards you will seem higher • the wavelength will seem shorter •The frequency of it moving away from you will seem lower • the wavelength will seem Longer |
| What is the big bang theory | The theory states that about 13.7 billion years ago all the matter in the Universe was concentrated into a single incredibly tiny point |
| What is wrong with the big bang theory | • it's not the the whole explanation of the universe • the big batheory predicts that the universes expansion should be slowing down but actually it's speeding up |
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