P2

What are photocells?
They are cells which convert light energy into kinetic energy and then into electrical energy.
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What are some advantages of solar energy?
They are a renewable source, they don't produce any pollution and they have a long life.
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What are some disadvantages of solar energy?
They can't be used at night because there's no sunlight, they're expensive to manufacture and they're not very reliable.
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What are greenhouse gases?
Carbon dioxide, water vapour and methane are gases found in the Earth's atmosphere which stop heat from the Earth radiating into space.
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How can you calculate the efficiency of a power station?
efficiency = (electrical energy output / fuel energy input) x 100%
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What are direct currents?
Direct currents travel in one direction and the voltage stays the same throughout.
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What are alternating currents?
Alternating currents switch between a positive and a negative voltage which results in the current reversing rapidly.
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How does a thermal power station work?
Fuel is burnt, releases heat --> heat boils water and turns into steam --> steam goes along pipe and turns a turbine --> turbine turns a generator --> generator makes electricity --> cabels carry electricity to buildings.
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What are transformers?
Transformers are used to increase or decrease voltage. Step up transformers give a higher output voltage than input voltage and step down transformers give a lower output voltage than input voltage.
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What are amps (a) and voltage (v)?
Electricity is the flow of electrons that carry charge around a circuit. The flow of electrons is called the current and is measured in amps (a) and the voltage (v) is the amount of energy the electrons have at any point.
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How do you work out power?
Power (watts, w) = voltage (volts, v) x current (amps, a)
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How do you work out the energy transferred?
Energy transferred (kilowatt hours, kWh) = power (kW) x time (h)
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What is off peak electricity?
Off peak electricity is a second electricity supply which is only available from 11pm to 6am. This electricity is cheaper to use but there is an extra charge for having this meter.
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How do you work out the total cost for electricity?
Total cost = number of kilowatt hours x cost per kilowatt hour.
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Radiation that we're exposed to all the time which is caused by natural sources such as; rocks, soil, cosmic rays and artificial sources such as; nuclear power and medical uses
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They are made of three smaller particles; a nucleus made of protons and neutrons and electrons orbiting around the nucleus.
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What are alpha particles?
They are very large so it's difficult for them to travel through materials which is why they're stopped by paper.
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What are beta particles?
Beta particles are slightly smaller but are still quite big so they are stopped by 3mm of aluminium.
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What are gamma rays?
Gamma rays are the smallest so it's easier for them to travel through materials but are stopped by 3cm of lead.
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What is an isotope?
An isotope is the same element with a different number of neutrons.
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What is uranium?
It is a radioactive element which decays to become a more stable isotope.
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What are alpha particles made of?
Two neutrons and two positive protons.
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What are beta particles made of?
One negative electron.
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What are gamma rays made of?
Electromagnetic wave.
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What is ionising?
Losing or gaining an electron.
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What are some problems with dealing with radioactive waste?
It remains radioactive for a long time, there is a terrorist risk and it must be kept out of groundwater.
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What are some ways which you can dispose of radioactive waste?
Low level waste can go in landfill sites, it can be enclosed in glass and left underground or you can reprocess it.
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How was the moon formed?
It was formed in a collision between the Earth and a Mars sized planet. The planets collided and the iron cores from them merged to form the Earth. The less dense parts were thrown out and now orbits the Earth.
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Other cards in this set

Card 2

Front

What are some advantages of solar energy?

Back

They are a renewable source, they don't produce any pollution and they have a long life.

Card 3

Front

What are some disadvantages of solar energy?

Card 4

Front

What are greenhouse gases?

Card 5

Front

How can you calculate the efficiency of a power station?