Karteikarten
P2 - Living for the future (Energy Resources) - Flash Cards
Karten in diesem Stapel (68)
- 1Physics: Living for the future (Energy Resources) P2 Flash CardsBy Aneeqa Ahmed
- 2Advantages of PhotocellsThe advantages of Photocells are: They are robust and don't need much maintenance, don't need fuel and don't need long power cables, cause no pollution and don't contribute to global warming and they use a renewable energy resource.
- 3Disadvantages of PhotocellsThey do not produce electricity when it is too dark or cloudy.
- 4How photocells work (Stage 1 + 2)1. A photocell contains two pieces of silicon joined together to make a p-n junction.
2. One piece has an impurity added to produce an excess of free electrons -n type silicon. - 5How photocells work (Stage 3 + 4)3. The other piece has a different impurity added to produce an excess of free electrons - p type silicon.
4. Sunlight contains energy packets called photons. - 6What a Photon isPhotons cause free electrons to move producing an electric current.
- 7What the output from a photocell depends on:1. The light intensity.
2. The surface area exposed.
3. The distance from the light source. - 8Passive Solar Heating 1The sun is very hot and produces infrared radiation with a very short wavelength.
Glass is transparent to this short wavelength radiation. - 9Passive Solar Heating 2The walls and floor inside a building absorb this radiation, warm up and re-radiate infrared radiation.
The walls and floors aren't as hot as the sun and the wavelength radiated is therefore longer. - 10Passive Solar Heating 3Glass reflects this longer wavelength radiation back inside the building.
In the southern hemisphere the big windows in a house face north towards the sun and in the northern hemisphere they face south. - 11Heat from the sunSolar reflectors are moved by computer to make sure they are always facing towards the sun.
- 12Energy from the wind:Wind is a renewable form of energy, but it does depend on the speed of the wind.
Wind turbines don't work if there is no wind, nor if the wind speed is too great. - 13Wind Farms - (Advantages and Disadvantages)Advantages: They don't contribute to global warming, nor do they pollute the atmosphere.
Disadvantages: They can be noisy, take up a lot of space and people sometimes complain about the view being spoiled. - 14How a current from a dynamo can be increasedThis can be increased by:
Using a stronger magnet, Increasing the number of turns on the coil and Rotating the magnet faster. - 15What is an OSCILLOSCOPEThis is the output from a dynamo which can be displayed on one of these.
An oscilloscope trace shows how the current produced by the dynamo varies with time. The time 1 complete cycle is called the period of the alternating current. - 16Simple GeneratorsThis consists 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. - 17How a Current can be produced.It can be produced if the coil remains stationary and the magnets move.
(Generators at power stations work on the same principle) - 18Power StationsIn conventional power stations, fuels are used to heat water:
Water boils to produce steam, steam at high pressure turns a turbine and the turbine drives a generator. - 19Energy EfficiencyEfficiency is a measure of how well a device transfers energy.
Energy in a power station is lost in the boilers, generators and cooling towers. - 20Greenhouse gases 1Most wavelengths of electromagnetic radiation can pass through the earth's atmosphere, but infrared radiation is absorbed.
- 21Carbon Dioxide occurs naturally because of:Natural forest fires, volcanic eruptions, decay of dead plant and animal matter, its escape from the oceans and respiration.
(Manmade carbon dioxide is caused by burning fossil fuels, waste incineration, deforestation and cement manufacture. - 22Water VapourThis is the most significant greenhouse gas:
Almost all of the water vapour occurs naturally, about 0.001% comes from human activities and 1/2 of the greenhouse effect is due to water vapour and a 1/4 due to clouds. - 23Greenhouse Gases 2Methane is produced when organic matter decomposes in an environment lacking oxygen.
Natural sources include wetlands, termites and oceans. Man-made sources include the mining and burning of fossil fuels, digestive processes of animals (cattle), rice paddies and waste in landfills. - 24The Greenhouse EffectThe electromagnetic radiation from the sun has a relatively short wavelength. This is absorbed by and warms the earth, the earth then re-radiates the energy as infrared radiation with longer wavelength. The longer wavelength radiation is absorbed by greenhouse gases which warms the atmosphere.
- 25Dusts in the atmosphereThis can have opposite effects:
The smoke from factories reflects radiation from town back to earth, the temp rises.
The ash cloud from a volcano reflects radiation from sun to space, temp falls. - 26Measuring PowerElectrical appliances usually display a power rating in watts (W) or kilowatts (KW).
The unit of electrical energy used in the home is the kilowatt-hour (KWH). - 27Measuring Power (Equations)Power = Voltage x Current
Energy Supplies = Power x Time
Cost of Electricity used = Energy Used x Cost per KWh - 28Cheaper ElectricityWe pay less for the electricity during the night, when much isn't needed but it still has to be produced.
- 29Energy SourcesSome energy sources are more appropriate than others in a particular situation because of the factors below:
availability, ease of extraction, effect on the environment and associated risks. - 30The National GridThis is a series of transformers and power lines that transport electricity from power stations to the consumer.
High voltage leads to - Reduced energy loss, reduced distribution costs and cheaper electricity for consumers. - 31Transmission LossesWhen a current passes through a wire it gets hot. The greater the current, the hotter the wire.
When a transformer increases the voltage, current is reduced means less heating effect, less energy lost to the environment. - 32Ionisation 1Atoms contain the same number of protons and electrons - they are neutral.
Ionisation involves gaining or losing electrons: When the atom gains electron it is negatively charged and when electrons are lost it is positively charged. - 33Formation of IonsThis can cause chemical reactions.
Such reactions may disrupt the normal behaviour of molecules in the body. This can cause strands of DNA to break or change; Protein molecules may change their shape and these effects are potentially harmful. - 34Properties of Ionising Radiation 11. Alpha, Beta and Gamma radiations come from the nucleus of an atom.
2. Alpha radiation causes most ionisation and gamma radiation cause the least. - 35Properties of Ionising Radiation 23. Alpha Radiation is short ranged (a few centimetres) and is easily absorbed by a sheet of paper or card.
4. Beta Radiation has a range of about 1m and is absorbed by a few millimetres of aluminium. - 36Property of Ionising Radiation 35. Gamma radiations is more penetrating, a few centimetres of lead would stop radiation, some can pass through several metres of lead or concrete.
6. Experiments can be done to check the penetration, check background radiation. - 37Uses of Radioactivity Smoke Alarms (Alpha Radiation)They contain a source of Alpha Radiation, the radiation ionises the oxygen and nitrogen atoms in the air which causes small electric currents. When smoke fills the detector during a fire the air isn't ionised so the current is less and the alarm makes a sound.
- 38Uses of Radioactivity Paper rolling Mill (Beta Radiation)Thickness in a paper rolling mill can be controlled using a source of beta radiation and a detector:
The amount of radiation passing through the sheet is monitored and the pressure on the rollers adjusted accordingly. - 39Uses of Radioactivity Sterilising Medical Instruments (Gamma radiation)Gamma radiation kills microbes and bacteria so it can be used for sterilising medical instruments. It can also be used to check for leaks in pipes or welds.
(Passage of blood and other substances can be traced by Gamma and Beta sources. - 40Nuclear WastePlutonium is a waste product from nuclear reactors which can be used to make nuclear bombs.
Some low level radioactive waste can be buried in landfill sites, high level waste is encased in glass and buried seep underground or reprocessed. - 41Radioactive WasteThis can remain radioactive for thousands of years. it must be stored where it cannot leak into natural underground water supplies and hence into lakes and rivers.
It is not suitable for making nuclear bombs but can be used by terrorists to contaminate water supplies or land. - 42Advantages and Disadvantages of Nuclear Power StationsAdvantages: Fossil fuel reserves are not used and no greenhouse gases are discharged into the atmosphere.
Disadvantages: Very high maintenance and decommissioning costs, risk of accidents. - 43CometsThey have very elliptical orbits:
They pass inside the orbit of Mercury and go out well beyond the orbit of Pluto. - 44MeteorA Meteor is made from grains of dust that burn 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' - 45Black HolesBlack Holes are formed where large stars used to be:
You cannot see a black hole because light cannot escape from it.
It has a large mass but a very small size. - 46Centripetal ForceMoons orbit planets and planets orbit stars because of this force acting on them.
1. Centripetal Force acts towards the centre of the circular orbit.
2. Gravitational attraction is the source of the centripetal force. - 47Exploring the PlanetsUnmanned probes can go where conditions are deadly for humans.
Spacecrafts carrying humans have to have large amounts of food, water and oxygen aboard. - 48Astronauts (Clothing in Space)They can wear normal clothes in a pressurised spacecraft. Outside the spacecraft they need to wear special space suits for example:
A dark visor (stops becoming blind), Suit (has source of oxygen for breathing). - 49Space 1When travelling in space, astronauts are subjected to lower gravitational forces.
Unmanned spacecraft cost less and don't put lives at risk, the spacecrafts need to be reliable because there is usually no way of repairing them when they break down. - 50Space 2All bodies in space, including planets were formed when clouds of gas and dust collapsed together due to gravitational forces of attraction. The mass of an object determines its gravitational force.
- 51Distances in SpaceDistances are very large. Light travels at 300 000 km/s : light from the sun takes about 8 minutes to reach us on earth. Light from the nearest star takes 4.22 years approximately.
(A light year is the distance light travels in one year) - 52AsteroidsAsteroids are mini planets or planetoids orbiting the sun:
- Most orbit between Mars and Jupiter
- Are large rocks that were left over from the formation of the Solar System. - 53Origin of The Moon 1Scientists believe our Moon was a result of the collision between 2 planets in the same orbit. The iron core of the other planet melted and joined with the Earth's core, less dense rocks began to orbit and they joined together to form our moon.
- 54Origin of The Moon 2There is scientific evidence to support this:
- The average density of the Earth is higher than the density of the Moon.
- There is no iron in the Moon.
- Moon has the same oxygen composition as the Earth, but rocks on Mars and other parts have different oxygen composition. - 55Comets Orbit (Most Comets pass inside the orbit of Mercury and well beyond the orbit of Pluto)As the Comet passes close to the sun, ice melts and solar winds blow the dust into the comets tail which faces away from the sun. Scientists constantly monitor these and other near-Earth objects. The speed of a comet increases as it approaches the sun and decreases away. (gravitational)
- 56NEO's (Near-Earth Objects)If an NEO is on a collision course with Earth it could be the end of life on Earth.
To avoid this, 1 option would be to explode a rocket near to the NEO which could alter its course enough to miss Earth. - 57The UniverseExpanding - Almost all of the galaxies are moving away from each other with further galaxies moving faster.
- 58Definition of The Red ShiftWhen a source of light is moving away from an observer, its wavelength appears to increase which shifts light towards the red end of the spectrum.
- 59NebulaThis is a swirling cloud of
gas and dust - 60Nebula CloudsThey are pulled together by gravity and, as the spinning ball of gas starts to get hot, it glows.
This protostar cannot be seen because of the dust cloud. - 61Gravity and StarsGravity causes the star to become smaller, hotter, brighter and after millions of years. The core temperature is hot enough for nuclear fusion to take place, as hydrogen nuclei join together to form helium nuclei, energy is released and the star continues to shine while there is enough hydrogen.
- 62A star's life history (Small Stars)Small Stars shine for longer than large stars because they have less hydrogen but use it up at a slower rate and what happens at the end of a star's life depends on its size.
- 63The end of a star's life (Medium Sized Star)A medium sized star like the sun becomes a red giant, while the core contracts, the outer part cools and changes colour from yellow to red and expands.
Gas shells called planetary nebula are thrown out, the core is a white dwarf shining brightly but becomes a black dwarf by cooling. - 64The end of a star's life (Large Stars)Become red supergiants, as core contracts, the outer expands, the core collapses to form a neutron star and there is an explosion called a supernova.
neutron stars are dense, remnants from a supernova merge to create new stars and the core continues to collapse, more dense - 65The end of a star's life (Black Hole)Large star's could form a black hole.
A black hole has a very large mass concentrated in a small volume so it has a very large density and its large mass means it has a strong gravitational pull. - 66StarsThey are formed from nebulae and will eventually become:
Red giants
White dwarfs
finally, Black dwarfs - 67AsteroidsMost asteroids orbit between Mars and Jupiter but some pass closer to the Earth.
Constantly being monitored.
An asteroid strike could cause climate change and species extinction - 68The UniverseIt is explored by telescopes on the Earth and in Space.
Large distances mean that it takes longer for information to be received and inter-galactic travel unlikely.
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- Karteikarten am P2 - Living for the future (Energy Resources) - Flash Cards, erstellt von aneeqaahmed am 13/04/2015.
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