Fichas
OCR Gateway Physics P2
Fichas del conjunto (35)
- 1What are the advantages of photocells?-They are robust and don't need much maintenance.
-no fuel or long power cables are needed.
-No pollution and they don't contribute to global warming.
-they use a renewable energy source resource. - 2How does a photocell work?-A photocell is made up of two pieces of silicon joined together to make a p-n junction. One piece has an impurity added to produce an excess of free electrons - n-type. Whereas the other piece has a different impurity to give an absence of free electrons p-type. Photons from energy packets form the sun, cause free electrons to move, producing an electric current.
- 3What destine output of a photocell depend on?-Light intensity.
-Surface area exposed.
-distance from the light source. - 4How can the current from a dynamo be increased?-Using a stronger magnet.
-increasing the number of turns on the coil.
-rotating the magnet faster. - 5What does a simple generator consist of?-Of a coil of wire rotating between the poles of a magnet.
-the coil cuts through the magnetic field as it spins.
-a current is produced in the coil. - 6How can a current also be produced when the coil does not move?-Instead the magnets can move.
- 7How do conventional power stations produce power?-Water boils and produces steam.
-Steam at a high pressure turns a turbine.
-the turbine drives a generator to produce electricity to then be taken to a transformer. - 8How does carbon dioxide naturally occur in the atmosphere?-natural forest fires.
-volcanic eruptions.
-decay of dead plants and animals.
-respiration.
-escaping from the ocean. - 9How is man-made carbon dioxide cause?-Burning of fossil fuels, waste incineration, deforestation and cement manufacture.
- 10What is the most significant greenhouse gas?And why?-Water vapour:
-As almost all water vapour occurs naturally.
-0.001% comes from human activity.
-Half of the greenhouse effect is due to water vapour and a further quarter is due to clouds. - 11How is methane produced?-When organic matter decomposes in an environment lacking oxygen:
-natural sources consist of wetlands, termites and oceans.
-man-made sources consist of the mining and burning of fossil fuel, digestive processes of animals,rice paddies and the burying of waste in landfills. - 12What is the greenhouse effect?-The electromagnetic radiation from the Sun has a relatively short wavelength. This radiation is absorbed by and warms the Earth
- 13What affects does dust have in the atmosphere?-the smoke from factories reflects radiation from the town back to earth, the temperature rises as a result.
-the ash clouds from a volcano reflects radiation from the sun back into space, the temperature falls as a result. - 14Why is electricity cheaper at night?-Electricity is cheaper at night as it is not needed as much, but still has to be produced.
- 15What is the national grid?-Is a series of transformers and power lines that transport electricity from power stations to consumers.
- 16Transformers in the national grid are used to step up the voltage to 400,000V, why is high voltage wanted?-Reduced energy loss, was a high current leads to heat energy being transferred to the environment.
-reduced distribution costs.
-cheaper electricity for customers. - 17Atoms are neutral what does this mean?-They contain the same number of protons and electrons.
- 18What does ionisation involve?-involves gaining or losing electrons:
-when the atom gains electrons it becomes negatively charged.
-when the atom loses elections it becomes positively charged. - 19What sort of chemical reactions can ion cause?-such reactions may disrupt the normal behaviour of molecules with the body, e.g. may cause DNA strand to break or change, which is potentially harmful.
- 20where does alpha, beta and gamma radiations come from in an atom?-From the nucleus.
- 21Which radiation causes the most ionisation and the least?-Alpha causes the most ionisation and gamma the least.
- 22How do smoke alarms work with a source of alpha radiation?-the radiation ionises the oxygen and nitrogen atoms in air, causing a very small electric current, which is detected. When smoke fills the detector in the alarm during a fire, the air is not so ionised so there is less current and the alarm sounds.
- 23What is gamma radiation used for?-Gamma radiation kills microbes and bacteria so it is used to sterilise medical instruments. Or for leaks in pipes in drains.
- 24What is plutonium?-Is a waste product from nuclear reactors which can be used to make nuclear bombs.
- 25how is radioactive waste dealt with?-Low level radioactive waste can be buried in landfill sites.
-High level is encased in glass and buried deep underground or reprocessed. - 26why is the storage of radioactive waste important?-As it can remain active for thousands of years, and must be stored well away from any water sources. Plus it could also be a potential target by terrorists to contaminate land or water supplies.
- 27What are advantages to nuclear power?-Fossil fuel reserves aren't depleted and no greenhouse gases are discharged into the atmosphere.
-Disadvantages are its very high maintenance and decommissioning costs, and there is a risk of accidents. - 28What sort of orbits do comets have?-They have elliptical orbits: in which they pass inside the orbit of mercury and go out beyond pluto's orbit.
- 29What is a meteor made up of?-Grains of dust that burn up as they pass through the earth's atmosphere: they heat the air around them which glows and the streak is known as a 'shooting star'.
- 30Where are black holes formed?-Where large stars used to be:
-you cannot see them as n light can escape them.
-It also has a very large mass but very small size. - 31Why do moons orbit planets, and planets orbit stars?-Because a centripetal force acts upon them:
-centripetal forces act towards the centre of the circular orbit.
-Gravitational attraction is the source of the centripetal force. - 32Where do unmanned probes go?-Where the conditions are deadly for humans.
- 33How are spacesuits designed to be able to go into space?-dark visor stops astronaut from being blinded.
-is pressurised and has a supply of oxygen.
-surface of suit can withstand temperatures between 120-(-160)℃. - 34At what speed does light travel?-300 000km/s
- 35What are asteroids?-Mini-planets or planetoids orbiting the sun:
-they are large rocks left over from the formation of the solar system.
Información
- Descripción
- GCSE Physics Fichas sobre OCR Gateway Physics P2, creado por Carson Yeung el 18/06/2015.
- Creado por
- Carson Yeung
- Visitas
- 52
- Historial
-
- Creado por Grace Bennett · 18 jun 2015
- Copiado por Carson Yeung · 18 jun 2015
- Valoración