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165 Cards in this Set
- Front
- Back
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Name the 8 types of energy stores |
Thermal Kinetic Gravitational potential Elastic potential Chemical Magnetic Electrostatic Nuclear
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Name the ways energy can be transferred |
Mechanically Electrically Heating Radiation |
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What is a system? |
A single object or group of objects |
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What is a close system? |
A system were neither matter nor energy can enter or leave |
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What is the net change in total energy of a closed system? |
It is always zero because no matter or energy can enter or leave |
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What does work done mean? |
Work done means energy transferred |
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What is meant by the conservation of energy principle? |
That energy can be transferred usefully, stored or dissipated but can never be created or destroyed |
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When energy is transferred between stores, does all the energy get transferred usefully? |
No because not all the energy goes where you want it to go. Some is dissipated when the transfer takes place |
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What does specific heat capacity mean? |
The amount of energy needed to heat 1kg of a substance by 1•c. |
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Equation linking energy transfer to specific heat capacity |
Change in thermal energy = mass X specific heat capacity X temperature change |
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How is kinetic energy transferred when an object speeds up? |
Energy is transferred to the store |
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How is kinetic energy transferred when an object slows down? |
Energy is transferred away from the store |
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Formula for kinetic energy |
Kinetic energy = 1/2 X mass X speed^2 |
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Example of chemical energy |
Food, fossil fuel |
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Example of nuclear energy |
Energy released from nuclear fission |
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Example of thermal energy |
Boiling water |
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Example of light energy |
Sun, bulb |
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Example of gravitational potential energy |
Book on shelf, anything off the ground |
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Example of elastic potential energy |
Stretched elastic band |
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Example of kinetic energy |
Moving car/plane |
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Example of electrostatic energy |
Static hair from balloon |
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Example of magnetic energy |
Normal magnets, compass |
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Equation linking power and energy transferred |
power=energy transferred /time |
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Equation linking power and work done |
Power=work done/time |
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What is conduction? |
Conduction is where vibrating particles transfer energy to neighboring particles |
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What is convection? |
Convection is where energetic particles move away from hotter to cooler regions |
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Units of specific heat capacity |
J/Kg degreeC |
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Two ways to reduce energy loss when transferring |
Lubrication and Insulation |
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Why do you need lubrication for energy transfer? |
Lubrication reduces frictional force which causes some energy in the system to be dissipated |
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What do insulators do? |
Insulators reduce the rate on energy transfer by heating |
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Examples of insulators in a house |
Loft insulation Double glazing Cavity walls Draft excluders |
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Efficiency for energy transfer equation |
useful output energy transfer/total input energy transfer X100 |
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Efficiency for power equation |
useful power output/total power inputX100 |
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What makes a device efficient? |
The less energy 'wasted' (transferred to useless energy stores) the more efficient it is |
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What is most common useless energy store for energy to be transferred to? |
Thermal |
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What does non-renewable energy mean? |
One day the energy resources will run out |
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Examples of non-renewable energy resources |
Fossil fuels (coal, oil and gas) and nuclear fuel (uranium and plutonium) |
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What does renewable energy mean? |
That the energy resource will never run out |
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Examples of renewable energy? |
Wind, solar, water waves, hydro-electricity, bio- fuel, tides, geothermal |
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Non-renewable resources for transport examples |
Petrol and diesel and coal |
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Renewable resources for transport |
Biofuel |
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Non-renewable resources for heating |
Coal, electric heaters using electricity generated from non-renewable resources |
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Renewable resources for heating |
Geothermal, solar water heaters, bio-fuel |
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How does wind energy work? |
Turbines are put in an exposed area, each turbine has a generator put in it, the rotating blades turn the turbine to produce electricity |
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Advantages of wind power |
No pollution, no fuel costs and minimal running costs, no permanent damage to the landscape |
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Disadvantages of wind power |
Can ruin scenery, very noisy, relies on the wind, initial costs are high |
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How does solar energy work? |
They generate electric currents directly from the sunlight |
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Advantages of solar energy |
No pollution, very good in sunny countries, no energy cost and low running cost |
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Disadvantages of solar energy |
Only useful in daytime, can't increase power output, initial cost is high |
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How does geothermal energy work? |
Possible in volcanic areas, hot rocks and the decay of elements releases energy |
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Advantages of geothermal energy |
Free energy, very reliable, does little damage to the environment |
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Disadvantages of geothermal energy |
Aren't many suitable locations, cost of building the power plant can be high compared to the energy output |
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How does hydro electric power work? |
Works by flooding a valley by building a big dam. Water is allowed out through turbines. |
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Advantages of hydro-electric power |
It can provide an immediate response to an increased demand for electricity, no pollution, no fuel costs and low running costs, no problem with reliability |
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Disadvantages of hydro-electric power |
Big impact on the environment because due to the flooding of the environment, initial costs are high |
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How does wave power work? |
Lots of small wave powered turbines located around the coast, the moving turbines are connected to a generator |
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Advantages of wave power |
No pollution, useful on small islands, no fuel costs and minimal running costs |
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Disadvantages of wave power |
Disturbing the sea bed, destroying habitats, spoiling views, hazards to boats, unreliable, initial costs are high |
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How does tidal power work? |
As the tide comes in the water fills up the estuary. It is then allowed out through turbines at a controlled speed. |
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Advantages of tidal power |
Reliable because tides always happen, no pollution, no fuel costs and minimal running costs |
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Disadvantages of tidal power |
prevents free access by boat, spoils the view, changes habitats, initial costs are high |
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How does bio-fuel work? |
Bio-fuels are renewable energy resources created from plant products or animal waste, they can then be burnt to produce electricity |
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Advantages of bio-fuel |
Fairly reliable, supposedly carbon neutral, |
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Disadvantages of bio-fuel |
They cost a lot, species loose their habitats, increases CO2 and methane emissions, deforestation because of fuel demands, can't respond to immediate energy demands |
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Why is non-renewable power so popular? |
There is enough to meet current demand, running costs are low, fuel extraction cost is low |
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Problems with non-renewable energy |
Release CO2 which contributes to the greenhouse effect and global warming releases sulfur dioxide which contributes to acid rain coal mining and power plants ruin landscape/spoil views Oil spillages cause environmental problems Nuclear power waste is dangerous Nuclear power overall cost is high |
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What is current? |
Current is the flow of electrons round a circuit |
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Unit for current |
Amperes (A) |
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How does current change in a series circuit? |
It stays the same all through the circuit |
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What do the electrons carry? |
Energy |
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What does an ammeter do? |
Measures current in a circuit |
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How does current change in a parallel? |
Current is split between the branches and they add up to the total current |
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What is potential difference? |
Potential difference is the driving force pushing electrons round the circuit |
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What is resistance? |
Resistance is anything that slows down the flow |
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Unit for resistance |
Ohms |
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Unit for potential difference |
Volts |
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The greater the resistance across a component... |
The smaller the current flow for a given potential difference |
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Equation for charge flow |
Q=IT |
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LED |
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What is the relationship between the length if the wire and the resistance? |
They are directly proportional, as the length of the wire increases the resistance increases |
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In an ohmic conductor, how are current and voltage related? |
They are directly proportional at a given temperature |
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How does the resistance change in an ohmic conductor? |
The resistance doesn't change at a given temperature. it is directly proportional to the potential difference |
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How does temperature effect resistance? |
As temperature increases, resistance increases |
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How does resistance change in a filament lamp with increased current. Why? |
As the current increases the resistance increases because as current increases the temperature of the filament increases. Higher temperature, higher resistance |
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What is resistance like in a diode? |
In one direction, current flows easily, if reversed they have a very high resistance |
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Resistance in LDRs |
When it is dark, the resistance is high, when it is light the resistance is low |
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Uses for LDRs |
Automatic night lights, burglar alarms, outdoor lighting |
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Resistance in thermistor |
When it is cold the resistance is high, when it is hot the resistance is low |
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Use for thermistors |
Temperature sensors, electric thermostats |
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How does potential difference change in a series circuit? |
The potential difference is shared between the various componants |
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How is resistance calculated in a series circuit? |
Add up all the resistance |
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How is resistance calculated in a parallel circuit? |
The total resistance in the circuit is less than the resistance of the smallest resistor. Adding resisters decreases total resistance |
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Total potential difference across cells |
If they are added in the same way, their potential differences are added |
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How does potential difference change in a parallel circuit? |
Potential difference across each component is the same |
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What type of current is mains electricity? |
Alternating current |
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What type of current is a battery? |
Direct current |
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What is the voltage and frequency of UK mains? |
230V, 50Hz |
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Brown wire in plug |
Live wire, provides the alternating potential difference at 230V |
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Green and yellow wire in plug |
Earth wire, stops the appliance case form becoming live, 0V |
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Blue wire in plug |
Neutral wire, completes the circuit and carries away current, 0V |
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How does current effect energy transferred to the thermal energy? |
The higher the energy the more energy transferred to thermal energy stores |
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What is the national grid? |
The national grid is a giant system of cables and transformers that covers the UK and connects power stations to consumers |
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How is energy transferred efficiently across the national grid? |
The potential difference is increased which lowers the current meaning less energy is lost to the environment as heat |
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What potential difference is energy transferred as in the national grid? |
400 000V |
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Step up transfromer |
Increases the potential difference of the energy so it can be transferred efficiently |
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Step down transformer |
Reduces the potential difference of the energy so it is usable |
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How is static built up? |
Static is built from friction between two insulating materials. Electrons are transferred leaving the materials electrically charged |
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How is an electric field created? |
From any electrically charged object |
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What does it mean if the field lines are closer together? |
The electrical field is stronger |
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How do charges objects feel a force? |
When a charged object is put in the electric field of another they are either attracted or repulsed |
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How does a spark form? |
When an object has a high potential difference with an earthed object, it has a strong electric field. The strong electric field ionises the air (removes electrons) making it conductive so the current flows through it. |
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Particle model- solids |
strong forces of attraction particles in fixed regular arrangement little energy so vibrate around a fixed position generally the highest density |
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Particle model- liquid |
weaker forces of attraction between particles irregular arrangements particles are close but can move round each other Particles have more energy than solids, they move in random directions at slow speeds Less dense than solids |
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Particle model- gases |
almost no forces f attraction between the particles Particles have more energy than solids & liquids particles are free to move and travel in random directions at high speeds Gases are the least dense |
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How does heating a system increase its internal energy? |
Heating transfers energy to the object's kinetic energy stores |
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Change of state- solid to gas |
Sublimation |
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Change of state- gas to solid |
Deposition |
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Why are there flat spots on a heating or cooling graph? |
This is when the energy is being used to break/make bonds instead of increasing/decreasing the temperature |
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Define specific latent heat |
The amount of energy need to change 1Kg of a substance from one state to another without changing its temperature |
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Specific latent heat of fusion is between... |
Solids and liquids (melting, freezing) |
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Specific latent heat of vaporisation is between... |
Liquids and gases (evaporating, boiling, condensing) |
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How is pressure created in gases? |
Pressure is created when the high speed particles collide and exert a force |
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How does increasing the temperature of gas particles increases their pressure? |
As the particles are heated they gain kinetic energy meaning they move faster, this leads to more frequent collisions with a greater force, this increases the force exerted meaning a higher pressure |
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How does volume of a container change affect the pressure of gases? |
Increasing the volume means the particles will collide less often so pressure is decreased, decreasing the volume means more collisions and higher pressure |
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How are volume of a container and pressure of a gas related for a fixed temperature and mass? |
They are inversely proportional (as volume increases, pressure decreases) |
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How can you increase the temperature of a gas without heating? |
By doing work you apply a force which increases the gas's internal energy which can then increase the temperature |
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What did John Dalton do? |
Said atoms were solid spheres and that different atoms made up different elements
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What did J J Thompson do?
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Created the plum pudding model. He discovered particles called electrons that could be removed
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What did Rutherford and Marsden do?
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Gold foil experiment
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What did Niels Bohr do?
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Idea that electron where in shells that orbit around the nucleus
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What did James Chadwick?
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Proved existence of neutrons
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What did the gold foil experiment prove? |
Proves that most of the mass is concentrated in the center of the atom called the nucleus, this nucleus must be positive as it repelled the alpha particle. Also proves that as most particles went through, that the rest of the atom is empty space |
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What is an isotope of an element? |
A different form of the same element with the same number of protons but a different number of neutrons |
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Why do atoms decay? |
When an isotope is unstable is decays to become stable |
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Ionising radiation |
Radiation that knocks electrons off atoms |
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Alpha particle (what is it, range in air, penetrating power, ionising power) |
Two neutron and two protons, few cm in air, absorbed by a sheet of paper, strongly ionsing |
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Beta particle (What is it, range in air, penetrating power, ionising power) |
One electron, few meters in air, absorbed by sheet of aluminium, moderately ionising |
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How is a beta particle released? |
A neutron turns into a proton which releases an electron |
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Gamma rays (What is it, range in air, penetrating power, ionising power) |
Electromagnetic waves, travel long difference in air, absorbed by lead, weakly ionising |
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Can scientists predict radiation? |
No, it is a totally random process |
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How can you measure radiation? |
Using a Geiger-muller tube and counter which records the radiation counts reaching it per second |
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What is the activity of a radioactive source? |
Measured in becquerels, it is the rate at which a source decays |
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Half life definition (in terms of nuclei) |
The time taken for the number of radioactive nuclei of the isotope in a sample to half |
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Half life definition (in terms of activity) |
The time taken for the activity (and so count rate) to half |
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Define background radiation |
Low-level radiation that is around us all the time |
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What is irradiation? |
Exposure to radiation |
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How to reduce irradiation? |
Keeping sources in a lead-lined box, being behind a barrier or being in a different room |
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Define contamination |
Radioactive particles getting into or onto particles |
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How do you reduce contamination? |
Using protective clothing like gloves , using tongs, protective suits |
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Most dangerous radiation outside the body |
Beta and gamma radiation because they can both penetrate your skin and reach organs |
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Most dangerous radiation inside the body |
Alpha radiation because they do their damage in a localised area and can't penetrate back out the skin. |
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Risks of using radiation |
Damage cells which divide uncontrollably causing cancer They can ionise atoms causing tissue damage Kill cells making you ill |
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How can radioactive sources used in medical tracers? |
Gamma rays are taken int the body which can be traced to see if the body is working right. Must be gamma and have a short half life |
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How can radioactive sources be used to treat cancer? |
High doses can kill the cancer cells to destroy it, however this does damage normal cells making the patient feel ill |
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What is nuclear fission? |
Fission is the splitting of a larger nuclei into two lighter nuclei |
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What is release during nuclear fission? |
Two or three neutrons and gamma rays |
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How does a chain reaction of nuclear fission work? |
The neutrons released from the fission can be absorbed into another heavy nuclei causing more fission to occur. This is a chain reation |
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How does nuclear energy work? |
The gamma rays released by fission can be used to heat water causing steam to turn a turbine and generate energy |
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What is nuclear fusion? |
Fusion is where two light nuclei collide at a high speed to create a heavier nucleus. Some energy is also released. |
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Why do scientists want to create an energy generator through fusion and why haven't they so far? |
They want to create t because the energy fusion creates is much more then fission however they haven't found a way to create the temperatures and pressures needed for it. This makes it hard and expensive to build |
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Energy lost from the gravitational potential energy store= |
Energy gained in the kinetic energy store |
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What is meant by power? |
The rate of energy transfer or the rate of doing work |
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Explain conduction |
The particles in the part of the object being heated vibrate more and collide with each other. The collisions cause energy to be transferred between particles kinetic energy stores |
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Explain convection |
As the particles heat up they gain kinetic energy meaning they move around more. This increases the gap between the particles and so increases their volume. This makes them less dense. The less dense regions will rise above the cooler more dense regions causing a convection current. |
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What is meant by thermal conductivity? |
Its a measure of how quickly energy is transferred through a material by conduction |
