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32 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What are the advantages of photocells? |
They need no fuel, no long power cable, no pollution and use a renewable energy resource |
Fuel... |
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What are p-n junctions and how do they work? |
Made from 2 pieces of silicon N type has an impurity added to produce an excess of electrons and P type has a different impurity to produce absence of free electrons |
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Give 2 methods of increasing the output from a photocell |
Increase the light intensity, surface area exposed to light or decrease light source |
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How does glass keep houses warm at night? |
The walls and floor radiate infrared at a longer wavelength and is reflected by the glass so it stays inside the room |
Reflection... |
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What are the advantages and disadvantages of using wind turbines? |
Advantages: renewable, no pollution or global warming Disadvantages: unreliable, noisy and spoil landscape |
Reliable or not...? |
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How can the size of the current be increased on a dynamo? |
Use a stronger magnet, increase number of turns in the coil it spin faster |
After school physics... |
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How is a model generator different from at a power station? |
In a power station the turbines spin the generator, provide field, electromagnets turn inside cool where current is induced |
Turbines... |
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How do greenhouse gases cause the temperature of the earth to increase? |
By absorbing the longer wavelength infrared radiation |
Absorbing... |
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Which greenhouse is most significant? |
Water vapour |
Water... |
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What are the consequences of global warming? |
Polar ice caps melting, rising sea levels |
Antarctica… |
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What is the equation for power? |
Power=voltage x time Measured in kilowatt-hour |
Measured in... |
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How do you work out the cost of electricity used? |
Cost of electricity used=energy used x cost per kWh |
kWh... |
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Why are high voltages used in National Grid distributes? |
Reduces energy loss, and cost |
Energy... |
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How does using high voltage affect current in the wires? |
Current goes down as voltage goes up |
Up or down... |
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Negative ions are formed by: Positive ions are formed by: |
Negative- radiation causes atom to gain one or more electrons
Positive- radiation causes atom to lose one or more electrons |
Electrons... Less is more... |
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Medical use for gamma radiation? |
Radiotherapy, medical instruments and radioactive tracer |
Cancer... |
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What effects does ionisation have on human cells? |
Changes or mutations in DNA, protein molecules change shape which can lead to cancer |
Mutations... |
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How does a smoke alarm work? |
The radiation ionises the oxygen and nitrogen atoms in air this causes a very small electric current that is detected when smoke fills the detector in the alarm during a fire the air is not ionised the current is less and the alarm sounds |
Ionisation... Current... |
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Why is radioactive waste stored for so long? |
Because it can remain radioactive for thousands of years |
Years... |
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Describe a star |
It's a ball of hot glowing gas giving out energy from fusion |
Gas... |
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Describe a planet |
A spherical object orbiting a star which has cleared the neighbourhood of its orbit |
Orbits... |
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Describe a meteor |
Is made out of grains of dust that burn up as they pass through the earths atmosphere |
Dust... |
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What is a black hole? |
They are formed when a large star dies and you can't see them because light can't escape them |
Light... |
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What's the name of the force that keeps the moon in orbit around the earth? |
Centripetal force |
Centipede… |
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What is meant by the term light year? |
The distance light travels in one year |
Distance... |
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Why have asteroids not joined together to form another planet? |
Jupiters gravitational force |
Gravity... |
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What evidence suggests that asteroids have collided with earth in the past? |
Unusual metals found near craters, fossils found below the metal layer not above, fossil layers have been distributed by tsunamis |
Fossils... |
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Why is it important to monitor the paths of NEOs? |
Not track position accurately and deal with it it come close to earth To destroy send rocket with explosives to alter its path (pieces could hit earth) |
Positioning... |
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Which galaxies are moving fastest? |
The ones further away |
Far... |
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What is redshift? And how does it provide info on how fast a galaxy is moving? |
Light spectra from distant galaxies are shifted to the red end of the spectrum The greater the red shift the faster its moving |
Spectrum... |
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What happens to the cloud of gas and dust for it to produce a glowing star? |
Cloud pulled together by gravity, star becomes smaller hotter and bright the core tempos hot enough for nuclear fusion to take place which releases energy |
Gravity... |
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What happens to a medium sized star (like the sun) at the end of its life? |
Becomes a red giant and gas shells called planetary nebula are thrown out the core becomes a white dwarf and cools to become a black dwarf |
Dwarf... |
