Physics Core

  • Created by: T Colby
  • Created on: 11-06-15 14:38
What are the three types of heat energy transfer?
Radiation, conduction and convection.
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Heat radiation is the transfer of heat energy by what?
Infrared radiation (IR)
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Conduction and convection involve the transfer of energy by what?
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What is the main form of heat transfer in solids?
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What is the main form of heat transfer in liquids and gases?
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True or false. IR can be emitted by solids, liquids and gases.
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Fill in the gaps. Any object can both ... and ... IR, whether or not conduction or ... are also taking place.
Absorb, emit and convection.
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The bigger the temperature difference between a body and its surroundings, the faster/slower energy is transferred by heating.
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IR is the emission of what?
Electromagnetic waves
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Where is IR emitted from an object?
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An objects that's hotter than its surroundings emite more/less radiation than it absorbs.
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An object that's cooler than its surroundings absorbs more/less radiation than it emits.
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The hotter an object is, the more ... it radiates at any given time.
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Give two surfaces that you can feel IR on?
Recently parked cars bonnets and fires.
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What two things affect radiation?
Surface colour and texture.
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Dark, matt surfaces ... IR falling on them much better than light, shiny surfaces.
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Give two surfaces that are light and shiny.
Gloss white and silver
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Dark, matt surfaces ... more IR at any given temperature.
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Light, shiny surfaces ... a lot of the IR falling on them.
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What are the three states of matter?
Solids, liquids and gases.
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How are the particles in a solid arranged?
Close together in fixed and regular positions.
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Why are the particles in a solid close together in fixed and regular positions?
Strong forces of attraction between the particles.
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Do particles in a solid have much energy and what is the consequence of this?
Not much energy and can only vibrate in regular positions.
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How are the particles in a liquid arranged?
Particles are close together but can move past each other in irregular arrangements.
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Why are the particles in a liquid close together but in irregular arrangements?
Weaker forces of attraction between the particles.
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True or false. The particles in a liquid have less energy than those in a solid.
False, they have more.
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How do particles in a liquid move?
Random directions at low speeds.
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How are the particles in gases arranged?
Irregular positions.
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Why are the particles in gases arranged in irregular postions?
Almost no forces of attraction between particles.
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True or false. Particles in gases have more energy than those in liquids and gases.
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How do particles in a gas move?
Free to move in random directions at high speeds.
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What do you give more to when you heat a substance?
Kinetic energy (KE)
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What happens to substances when they gain KE?
Vibrate and move faster .
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What causes solids to melt and liquids to boil?
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Conduction of heat energy is the process where vibrating ... pass on their extra ... to neighbouring particles.
Particles and KE.
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In what type of solids is conduction faster?
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Close together particles will ... more when they gain KE.
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What are materials with larger spaces between their particles that conduct heat energy much more slowly?
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Why are metals good conductors?
Their electrons are free to move inside the metal and transfer energy.
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What two things are metals good at conducting?
Heat and electricity.
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Convection occurs when the more energetic particles move from the ... region to the ... region and take their heat energy with them.
Hotter and cooler
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Why can't convection occur in solids?
Particles can't move
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What are convection currents all about?
Changes in density
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What two main examples explain convection?
Immersion heaters and radiators
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What is condensation?
When gas turns to liquid
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Explain condensation.
Gas cools and particles slow down. They lose KE and the attractive forces between particles pull them closer together. The gas becomes a liquid.
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What is steam?
Invisible water vapour that is condensing to form tiny water droplets.
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What is evaporation?
When liquid turns to gas.
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How can particles near the surface of a liquid escape and become gas particles?
Travel at right direction to gain light and travel fast enough to overcome attractive forces of the other particles in the liquid.
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As particals evaporate from liquids the temperature of the liquid increase/decreases.
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The rate of evaporation is greater if what?
Temperature is higher, density is lower, surface area is larger and if airflow over the liquid is greater.
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The rate of condensation is faster if what?
Temperature of the gas is lower, temperature of the surface the gas touches is lower, density is higher and airflow is less.
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The bigger the surface area, the more ... waves that can be emitted from the surface.
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Why do car and motorbike engines have fins?
Because the surface area allows heat to transfer quicker.
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Name a device that is designed to limit heat transfer.
Vacuum flask.
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How does a vacuum flask limit heat transfer?
The vacuum stops all conduction and convection through the sides, silver walls on outside to limit radiation, insulating foam minimises heat conduction and the stopper reduces heat conduction.
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How do animal hairs on skin keep them warm?
Traps a thicker layer of insulating air on the skin which limits the amount of heat loss by convection and keep them warm.
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What happens to your blood when your body's hot?
Your body diverts it to the surface of your skin so that more heat can be lost by radiation.
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True or false. Generally animals in warm environments have small ears compared to animals of cold environments.
False, they have bigger ears to increase heat loss.
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Give five ways to reducing heat transfer in the home.
Double glazing, draught proofing, hot water tank jacket, loft insulation and cavity wall insulation.
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What makes insulation effective?
Big annual saving on heating bills.
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The most cost effective methods tend to be the what?
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What does cavity wall insulation do?
Reduces convection between bricks with foam and radiation across the gap. Also pockets of air in the foam reduce heat transfer by conduction.
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What does loft insulation do?
Fibreglass wool reduces conduction and radiation into the roof space from the ceiling.
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What does draught proofing do?
Strips of foam and plastic around windows and doors stop cold air draughts blowing in (reduce convection).
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What do hot water tank jackets do?
Fibreglass wool reduces conduction and radiation.
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What do thick curtains do?
Recuce heat loss by conduction and radiation.
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What do U-values show?
Shows the quality of an insulator. The better the insulator the lower the U-value.
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How are U-values represented?
W/m2K (2 means squared)
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What is specific heat capacity?
How much energy a substance can store and needed to raise the temperature of a 1kg substance by 1 degree celsius.
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What is the formula for specific heat capacity?
E=m(times)c(times)temperature change
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Do heaters have high or low specific heat capacities?
High so they can store large amounts of heat energy.
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True or false. Watwer has a really high specific heat capacity.
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Why is water ideal in central heating systems?
It is a liquid that can be moved around pipes and with a high specific capacity.
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What are electric storage heaters designed to do?
Store heat energy at night (when it's cheaper) and then release it during the day.
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How do electric storage heaters store heat energy?
Concrete or bricks which have a high specific heat capacity.
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True or false. Some heaters are filled with oil.
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Does oil have a higher boiling point than water?
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What are the nine types of energy?
Electrical, light, sound, kinetic/movement, nuclear, thermal/heat, gravitational potential, elastic potential and chemical.
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Give the two types of stored energy.
Potential and and chemical energy.
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What is stored energy?
Energy that isn't doing anything and it waiting to happen (turned into other forms).
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Energy can be ... usually from one form to another, ... or ... but can never be created or destroyed.
Transferred, stored and dissipated.
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When is energy only useful?
When it can be converted from one form to another.
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Give the order of energy transfer in batteries.
Chemical energy (arrow) electrical and heat energy.
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What is meant by a useful device?
They can transform energy from one form to another.
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The less energy that is waster the more ... a device is.
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How do you calculate efficiency?
Useful energy out/total energy in
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How can you calculate efficiency using power?
Useful power out/total power in
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How is wasted energy usually spread out?
As heat energy
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Ultimately all energy ends up as what energy?
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Why is wasted energy called wasted energy?
Because we can't do anything with it.
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What two things do you need to think about when choosing appliances?
Cost effectiveness and efficiency
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Give a useful wasted energy.
Heat from appliances can heat up rooms.
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What do sankey diagrams show?
Total energy in, useful energy and wasted energy.
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How is energy measured?
Joules (J)
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What is the equation for energy?
Energy=power (times) time
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Power is usually measured in what?
Watts or kilowatts
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What is a kilowatt hour?
Amount of electrical energy used by a 1kW appliance left on for 1 hour.
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Access to electricity effects standards of what?
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What is meant by a non-renewable resource?
It will run out
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What are the non-renewable resources?
The three fossil fuels and nuclear.
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What are the three fossil fuels?
Coal, oil and natural gas.
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What are the two types of nuclear fuels?
Uranium and plutonium.
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Are fossil fuels and nuclear non-renewable energies good for the environment?
No ther'ye not.
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What is meant by renewable energy resources?
They will never run out.
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What are the eight renewable energy resources?
Wind, waves, tides, hydroelectric, solar, geothermal, food and biofuels.
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Do renewable energy resources do more or less damage to the environment compared to non-renewable energy resources?
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What are the two negatives of renewable energy reosources?
Don't provide much energy and unreliable as they're sometimes effected by the weather.
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Energy sources can be burned to drive ... in power stations.
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What happens to fossil fuels chemical energy when its burned?
Converted to heat energy.
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What is heat energy used to heat in power stations to produce steam.
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What does steam turn which converts heat energy into kinetic energy.
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What is the turbine connected to which transfers kinetic energy into electrical energy.
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What produces heat to make steam to drive turbines in nuclear reactors
Nuclear fission of uranium and plutonium.
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Nuclear reactors take the longest/shortest time of all the power stations to start up.
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Natural gas power stations take the longest/shortest time of all the fossil fuel power stations to start up.
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How is wind power harvested?
Wind turbines which have their own generators to generate electricity from wind turning its blades.
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What are the negatives of wind turbines?
Spoil the view, very noisy, no power when wind stops, impossible to invrease demand and initial costs are quite high.
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What are the positives of wind turbines?
No pollution except for when they're manufactured and no permanent damage to the environment.
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How do solar cells generate electricity?
From sunlight
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What are the positives of solar cells?
No pollution except when they're manufactured, free energy and tiny running costs.
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What are the negatives of solar cells?
High initial cost, not practical and too expensive.
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How is hydroelectric power generated?
Building a damn to flood a valley, rainwater is caught and allowed through turbines and converted to electricity.
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What are the positives of hydroelectric power?
No pollution except from the construction of the damn, immediate response to electricty demand, no reliability problems, high initial costs, no fuel, minimal running costs, small scale and remote.
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What are the negatives of hydroelectric power?
Big negative impact on the environment, loss of habitat, unsightly and impacts humans.
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What is the main difference between hydrolectric power and pumped storage?
Pumped storage stores energy that has already been generated.
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How does wave power work?
Waves collide with generators around a coastline and the energy is converted to electricty.
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What are the positives of wave power?
No pollution except for construction, no fuel costs, minimal running costs, large scale energy and helpful for small islands.
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What are the negatives of wave power?
Spoils the view, hazard to boats, unreliable and high initial costs.
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What are tidal barrages?
Big damns built across river estuaries with turbines in them.
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How do tidal barrages generate electricty?
Tide builds estuary height and drives turbines. Water is then let out through the turbines at a controlled speed.
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What is the source of the energy from tidal barrages?
Gravity of the Sun and the Moon.
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What are the positives of tidal barrages?
No pollution except from construction, reliable, provide strong energy for peak demand, no fuel costs, minimal running costs and can generate lots of electricity.
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What are the negatives of tidal barrages?
No access for boats, spoils the view, alters habitats, tide heights can vary and high initial costs.
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What is geothermal energy?
Heat from underground.
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Where is geothermal energy only possible?
In volcanic areas where hot rocks lie near the surface.
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What is the source of energy from geothermal energy?
Heat from the slow decay of radioactive elements including uranium inside the Earth.
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How does geothermal energy work?
Steam and hot water rise to the surface which drive a generator.
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What are the positives of geothermal energy?
Brilliant free energy and can heat buildings directly without the conversion to electrical energy.
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What are the negatives of geothermal energy?
Not many suitable locations and high cost to build power plant.
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How are biofuels made?
From plants and waste.
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How are biofuels used to generate electricity>
They're burnt to heat up water and drive turbines and generators to generate electricty.
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True or false. Biofuels can be solids, liquids and gases.
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What are the positives of biofuels to generate electricity.
Can be used in some cars.
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Crops can be ... to produce ethanol and plant oils can be modified to produce ...
Fermented and biodiesel.
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Yes or no. All three fossil fuels release CO2 into the atmosphere when they're burned.
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What fossil fuel releases the most CO2 into the atmosphere?
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What is second and third to coal in releasing the most CO2 into the atmosphere when burned?
Second is oil and gas is third.
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Coal mining makes a mess of the ...
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Oil spillages cause serious ... problems, affecting mammal and birds that live in and around the sea.
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Nuclear waste is what?
Dangerous and difficult to despose of.
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Nuclear fuel is ... but the overall cost of nuclear power is ... due to the cost of power plants and final decommisioning.
Cheap and high.
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Name a nuclear disaster.
Chernobyl in 1986
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Biofuels are ... neutral.
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To grow biofuels many species lose their ...
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What is carbon capture and storage used to reduce?
CO2 building up in the atmosphere and the strength of thr greenhouse effect.
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How does carbon capture and storage reduce the discussed things?
CollectsCO2 from power stations before its released into the atmosphere. This is then pumped into empty gas and oil fields and stored.
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How is electricity distributed?
Via the National Grid
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What two things do you need to transmit power over large distances?
High voltage or high current.
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Why is high current a problem?
Lots of energy is lost through heat in cables.
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What is the best voltage for the National Grid?
400,000 V (Volts)
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What do transformers in the National Grid do?
Step up the voltage at one end for efficient transmission and reduce it to a lower, safer and usable levels at the other end.
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Electrical energy can be moved using overhead cables and cables buried in the ...
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Waves have amplitude, ... and ...
Wavelength and frequency.
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How is frequency represented?
Hertz (Hz)
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1 Hz is 1 wave per ...
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Transverse waves have ... vibrations
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In transverse waves the vibrations are ... at 90 degrees to the directon of energy ... of the wave.
Perpendicular and transfer.
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Longitudinal waves have vibrations along the same ...
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In longitudinal waves the vibrations are ... to the direction of ... transfer of the wave.
Parallel and energy.
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Give some examples of transverse waves.
Light and other electromagnetic waves, ripples on water, waves on strings and waves on a slinky spring.
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Give some examples of longitudinal waves.
Sound waves and ultrasound, shock waves e.g. seismic waves and a slinky spring when you push the end.
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How do you calculate wave speed?
Wave speed=frequeny (times) wavelength
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All waves can be reflected, ... and ...
Refracted and diffracted
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Reflection of light enters our ... and allow us to see things.
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Angle of incidence=angle of ...
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The image is the ... size as the object
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The image is the same ... as the object
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The image is laterally ... compared to the object
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What is reffraction?
Light of an object goes thorugh a material and changes direction.
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What is diffraction?
Light bends round obstacles and the waves spread out.
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What is the wavelength of light?
About 0.0005 mm
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When light of an object passes through a material the speeds of its waves ... and change direction.
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What is meant by the normal line?
90 degrees to the material or mirror.
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What are the order of the waves in the EM spectrum?
Radio waves, microwaves, infrared, visible light, ultra violet, x-rays and gamma rays.
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True or false. All waves travel at the same speed in a vacuum.
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EM waves with higher frequencies have ... wavelengths.
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Radio waves are used mainly for ...
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How do radio waves from one location reach locations miles away?
Radio waves diffract (bend) around the curved surface of the Earth.
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True or false. Short radio waves can reflect from the ionosphere in the Earth's upper atmosphere to travel long distances.
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Microwaves are used for satellite ... and ... phones
Communication and mobile.
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Why are microwaves used for the discussed purposes instead of radio waves?
They can pass through the Earth's watery atmosphere.
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True or false. Some people think that mobile phones can be bad for you as microwaves can be absorbed by the body.
True, however there isn't sufficient evidence.
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Infrared waves are used for remote ... and optical ...
Controls and optical
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How do infrared waves from controllers work?
Different wave patterns are sent to televisions to give different commands.
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Optical fibres can carry ... over long distances very ...
Data and quickly
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Visible light is used for ...
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How do cameras use visible light>
It is focused onto a light-sensitive film or electronic sensor. The lens aperture controls how much liht enters the camera and the shutter speed determines how long the film or sensor is exposed to the light.
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What are sound waves caused by?
Vibrating objects.
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Sound waves travel faster in solids than in ... and faster in ... than in gases.
Liquids and liquids
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Sound waves can reflect and ...
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Why can't sound waves travel in space?
It is mostly a vacuum.
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What are echoes?
Reflected sound waves.
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High frequency=high ...
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Low frequency=low ...
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Frequency is the number of complete vibrations each ...
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What are common units for sound waves frequency?
kHz (1000 Hz) and MHz (1000000 Hz)
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High frequency=... wavelength
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Loudness of a sound depends on what?
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The bigger the amplitude the louder the ...
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The universe is ...
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Light from other galaxies and objects in the universe is ... shifted
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What does the Doppler Effect describe?
Wave bevaviour for moving objects
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True or false. The Doppler Effect happens to both transverse and longitudinal waves.
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The further away an object in the universe is the greater its red ...
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What theory explains the start of the universe?
Big Bang Theory
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What was the Big Bang?
An explosion of a single point of compressed energy and matter that caused expansion still going on today.
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When did the Big Bang happen (supposidely)?
About 14 billion year ago.
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What is another theory that is differen to the Big Bang on how the universe started?
Steady State Theory
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What is cosmic microwave background radiation?
Low frequency electromagnetic radiation coming from all parts of the universe.
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Other cards in this set

Card 2


Heat radiation is the transfer of heat energy by what?


Infrared radiation (IR)

Card 3


Conduction and convection involve the transfer of energy by what?


Preview of the front of card 3

Card 4


What is the main form of heat transfer in solids?


Preview of the front of card 4

Card 5


What is the main form of heat transfer in liquids and gases?


Preview of the front of card 5
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