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GCSE Physics P1

What is thermal radiation? Energy transfer by electromagnetic waves.
Which objects emit thermal radiation? All objects.
What is the relation between the hotness of an object and thermal radiation emitted? The hotter the object, the more thermal radiation emitted.
Which is better at emitting thermal radiation. A dark matt surface, or a shiny, light surface? Dark matt surface.
Which is better at absorbing thermal radiation. A dark matt surface, or a shiny, light surface? Dark matt surface.
How does conduction occur in a metal? Free electrons transferring energy.
Why are non metals poor conductors? They do not contain free electrons.
Why are materials such as fibreglass good insulators? They contain pockets of trapped air.
In which states of matter does convection occur? Fluids (Liquids and Gases)
How does heating a fluid affect density? Makes it less dense.
What causes convection? A hot liquid or gas rising.
Why does a radiator have a large surface area? So it can lose heat easily.
Which loses heat more easily. Small or Large objects? Small objects.
How can heat loss from a building be reduced? -Aluminium foil behind radiators.-Cavity wall insulation.-Double glazing.-Loft insulation.
Does energy only exist in one form? No, energy exists in many forms.
Can energy transform into different forms? Yes- energy can transfor from one form to another.
What is 'The Conservation of Energy'? Energy cannot be created or desroyed.
Can energy be transferred from one place to another? Yes.
What is 'useful energy'? Energy in the place and form we need it.
What is 'wasted energy'? Not useful energy.
What happens to both useful and wasted energy? Transferred to surroundings as heat.
What happens as energy spreads out? It gets more and more difficuly to use for more energy transfers.
What unit is energy measured in? Joules.
How do you calculate the efficiency of a device? Useful energy (divided by) Total Energy
What effect does wasted energy have on efficiency? Causes inefficiency.
What is electrical energy? Energy transfer due to an electric current.
What are electrical devices used for? Heating, lighting, motorising, sound and visual.
What is the unit of power? Watt (W)
What does the unit 'Watt' mean. 1 Joule / Second
What is the calculation to find power? energy transferred (J) (divided by) time taken (seconds)
What is the calculation for energy transferred? (kWh) power (kW) x time (hours)
What is the calculation for price of energy transferred? number of KWh x cost per kWh
What is the national grid? A network of cables and transformers.
What are step up transformers used for in the national grid? To increase voltage levels from those used in powerstations, to those on the grid.
What are step up transformers used for in the national grid? To decrease voltage levels for use in homes.
Why is electricity transferred over the grid at high voltage? A higher voltage means less current, which means less energy lost as heat.
What are generators driven by in power stations? Turbines.
Which releases more energy per kilogram. Uranium or other fossil fuels? Uranium.
What is a wind tubine? An electricity generator on top of a tall tower.
What is a wave generator? A generator turned by the waves.
How are hydrolectricity generators turned? Water flowing downhill.
How does a tidal power station work? Traps each high tide and uses it to turn generators.
How can we use solar energy in the home? -Solar cells-Solar panels - used to heat water
Where does geothermal energy come from? Radioactive energy from sustances in the earth.
What do all fossil fuels produce? Greenhouse gases.
What do all Nuclear fuels produce? Radioactive waste.
What is a disadvantage of using renewable energy sources? Could affect plant and animal life.
List the electromagnetic spectrum in order of increasing wavelength. Gamma, X, U-V, Visible, Infra red, Microwaves, Radio.
At what speed do all electromagnetic waves travel through space? 300 Million m/s
What is the formula for wave speed? wavelength x frequency
What can absorb X-rays and gamma radiation? Dense materials (eg metal + bone)
Are there any disadvantages to humans regarding X rays and gamma radiation? Damage living tissue when they pass through it.
What are X-Rays used for? In hospitals to take radiographs.
What are Gamma rays used for? Kill bacteria in food, sterilise surgical equipment, kill cancer cells.
What are the effects of U-V radiation on humans? Harms skin and eyes.
How can we change the use of radio waves? By altering the frequency.
Which parts of the electromagnetic spectrum are used in fibre optics? Infra red and visible.
Are analogue signals constant in amplitude? No, they vary.
How many form of digital signal are there? 2 - (1 or 0)
WHat are the differences between analogue and digital transmission? Digital can carry more information and is free of noise and distortion.
What does a radioactive substance contain? Unstable nuclei.
How does an unstable electron become stable? By emitting radiation.
How many types of radiation are there? 3- Alpha beta gamma
Can we predict or influence radioactive decay? No- it is a random event.
What is alpha radiation stopped by? paper or a few cm of air
What is beta radiation stopped by? thin metal or a metre of air
What is gamma radiation stopped by? thick lead, unlimited in air
What is the 'half life' of a radioactive isotope? The time it takes for the number of nuclei of the isotope in a sample halves.
What happens to the number of unstable atoms and activity in one half life? Decreases to half.
What affects the use we can make of a radioactive substance? Half Life, Type of radiation
What happens to light from distant galaxies? It is red-shifted to longer wavelengths.
How far away are the most distant galaxies? 13,000 million light years.
Is the universe expanding? Yes.
How didthe universe begin? The big bang- a massive explosion from a very small point.
What is background microwave radiation? Radiation created just after the big bang.
Which electromagnetic waves are absorbed by the atmosphere? All but visible, radio and some UV.
What are satellite detectors used for? To make observations outside the visible and radio spectrum.
What are the advantages of a space telescope? Less atmospheric distortion, clearer image.
What are 2 sources of energy that can respond to surges in demnd for electricity? Hydroelectric, Tidal.
How does convection occur? Waater molucules gsin kinetic energy and move apart causing the region of water above the flame to expand and rise, carrying the heat with it.
Is nuclear a renewable energy source? No.
Are digital signals faster than analogue? No.
Is alpha radiation affected by a magnetic field? Yes, it is deflected to the negative.
Is beta radiation affected by a magnetic field? Yes, it is deflected to the negative. (opposite to alpha)
Is gamma radiation affected by a magnetic field? No it is not.
What is alpha radiation? Helium Nucleus (2 protons 2 neutrons)
What is beta radiation? A high speed electron from the nucleus. Emitted when a neutron changes to a proton and an electron. The proton remains in the nucleus.
What is gamma radiation? Very short wavelength electromagnetic wave from nucleus.
What affects rate of heat transfer? Shape/dimensions, Temperature difference between body and surroundings.
What are the disadvantages of using fossil fuels? Expensive to build, release greenhouse gases, radioactive waste etc.
Created by: james1234190

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