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AQA GCSE Physics Unit 1 - 20th June 2012 - MY UNOFFICIAL MARK SHEME

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    Updated Unofficial mark scheme: If there are any corrections, please say so and we'll discuss them.

    1)
    a) The stove emits radiation very well as it is a dark matt surface. This emmission can only happen if the surface absorbs hence, black matt is also a good absorber. 2 marks
    b) Efficiency = 90% or equivilent. 2 marks
    c) Wasted energy could be chemical,light,sound or heat(to stove). 1 mark
    d) environmental advantages of stove:less fossil fuels burnt,less C02,global warming and less S02,acid rain and the C02 is used up,by the wood when it grew to compensate for the C02 produced when burnt. 2 marks

    2)
    a) Graph interpretation: As the load in newtons increases, the amount of input energy also increases. The energy input increases constantly. 2 marks
    b) Energy transfer was 2 550 000J. 3 marks
    c) The motor uses gravitational potential energy or kinetic. 1 mark
    d) Wasted energy is dissipated into the surroundings and heats the surroundings. 2 marks

    3)
    a) Pumping cold water beneath the Earth's atmosphere where there are hot rocks. These hot rocks are used to heat up the water, turn it into steam and used to turn a turbine to generate electricity. 1 mark
    b) Energy is saved when the water is pumped and stored in dams so that energy can be used for future demands. Storage also allows fast production of energy when there is an unexpected surge. 2 marks
    c) - 6 MARK QUESTION

    Offshore wind turbines
    Advantages: Less pollutant gases and therefore makes Britain enviormentally friendly. It is also a renewable energy resource.
    Disadvantages: Could effect many habitats such as animals (Birds). The reliabilty of the wind turbines for producing electricity is not very high.

    Undersea National grid
    Advantages: Not effected badly in bad weather. The electricity gained could be used to reduce fossil fuels,C02,Global warming,S02,acid rain etc.More Hydroelectric electricity will allow more pump storage systems,allowing the national grid to be able to compensate for variations in demand of electricuty better.
    Disadvantages: Expensive as waterproof casing will be needed. It could also effect many sea creatures such as fish and other.

    4)
    a) Metals have free delocalised electrons which can help transfer energy through out the metal when they gain energy from the heat source. Particles also vibrate which increases the spread of energy throughout the metal. 4 marks
    b) (Not sure where this question goes so I just slipped it in here!) Gas particles have high amounts of kinetic energy. When they come in contact with a cold surface or an obstacle, the gas loses energy and the particles contract which means they become more closer together. This means the particles have less energy and the gas eventually turns into a liquid. 2 marks

    5)
    a) Double glazing has a lower U-Value meaning that less energy is transferred to the outside of the window and thus less condensation occurs because condensation is accelerated,with a higher surface temperature. 2 marks
    b) The U-Values for the double glazed windows was much more higher which makes them more effective at reducing heat transfer and acting as an insulator rather than the single glazed window. The double glazed companies are more expensive than the single glazed but they are still more effective. 3 marks

    6)
    a) Light rays drawn and reflected from bulb onto mirror,at two points,angle i=angle r and the 4 lines extend into the mirror until two of the lines cross,in the eyes perspective range, and then the virtual light bulb must then be same distance in front as behind the mirror. 4 marks
    b) It is a virtual image because it isn't generated by real light rays. 1 mark

    7) a)Microwaves and radiowaves have similar properties (Large wavelength, smaller frequency) and travel through a vaccum. 2 marks
    b) The signal from the radiowaves will be better than terrestrial waves because radiowaves can diffract more and therefore, spread more so that the signal can be picked up. Terrestrial waves on the other hand diffract but not enough for the signal will to be picked up. 3 marks
    c) Microwaves can pass through the Earth's atmosphere and to the sattelites in space. 2 marks
    d) Frequency = 1,200,000 Hz. 2 marks
    e) Independent scientists are used to avoid bias from the company itself. Independent scientists do not favour any side.

    8) a) 2880p - Escalator one. 3 marks

    9)a)Red shift is the increase in wavelength due to galaxy's moving further away from Earth. The big bang theory claims that the universe started with an explosion which caused expansion. Therefore, the planets are moving away from us. 3 marks
    b) After the big bang, high levels of CMBR were found in space which can be used as evidence to help prove the big bang theory. 1 mark
    c)The origin was the small initial point of matter. 1 mark
    d)lLarger wavelengths as the universe was exanding and therefore, more radiation would spread out. 2 marks
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    most of it is rightt


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    Thanks Popburrow! Thanks for taking the time!
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    (Original post by poistar)
    Thanks Popburrow! Thanks for taking the time!
    My pleasure. Any Science exam requests, please assure me.
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    (Original post by ThatGirlx)
    most of it is rightt


    This was posted from The Student Room's iPhone/iPad App
    Good to know. Have any idea what questions are missing? I could go over them as well!
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    (Original post by popburrow)
    Good to know. Have any idea what questions are missing? I could go over them as well!
    Chemical Energy is wrong-it is stored energy so Chemical Energy is transferred to heat-it is the start of the energy transfer Chemical-Sound+Heat+Light+Heat(to stove).Also,do you think that the stove could have been designed to allow convection currents,to be set up because the stove is open?Also,Question 5a)The condensation was outside the window and it is because it has a lower U-Value meaning that less condensation because the outside of the window will be colder for double glazing.The frequency was 1,200,000HZ.The light rays are not just reflected from the light bulb to the mirror to the eye.
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    1c - I and my friends did light
    and for 7b its the radiowaves can diffract, not refract

    Otherwise i'd say pretty accurate mark scheme
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    Very good!
    only issues: was motor gravitational or kinetic? it clearly converts to movement energy but would either be accepted as mark?
    5a) - this involved condensation so particle answer may not be correct; i am not sure.
    6b) - virtual - rays of light do not merge where they appear
    8c) - what was the question - don't think i put that but might have done; can't remember question!
    9d) - I agree - the wavelengths would decrease, for 2 marks I think a statement needs to be made about cooling + expansion of universe + relative reduction in frequency of the waves to microwaves - thus you would expect further decrease in wavelength

    Based on this, pretty confident i got at least 50/60 - which should be A*. thanks a lot!
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    Also 1a is it's matt black AND metal as stated in the question. Matt black is good absorber and emitter and metal is a good conductor. 2 Mark question required 2 specs
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    (Original post by Dalek1099)
    Chemical Energy is wrong-it is stored energy so Chemical Energy is transferred to heat-it is the start of the energy transfer Chemical-Sound+Heat+Light+Heat(to stove).Also,do you think that the stove could have been designed to allow convection currents,to be set up because the stove is open?
    You have a very good point about Chemical Energy. However, as it is supplied, the chemical energy is used up and gradually wasted. The answer in the mark scheme would most probabaly be heat, light or sound but they may even add chemical. Not sure but well corrected.
    The stove question was mainly targeted about Infrared Radiation (IR). Whenever there is a question about IR, it will depend on the surface and nothing else. The question for the stove did give away a clue to how the stove had a matt black casing.
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    I think you mixed up the frequency question with the Specific heat capacity one.
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    (Original post by walkerbusinessfood)
    Very good!
    only issues: was motor gravitational or kinetic? it clearly converts to movement energy but would either be accepted as mark?
    5a) - this involved condensation so particle answer may not be correct; i am not sure.
    6b) - virtual - rays of light do not merge where they appear
    8c) - what was the question - don't think i put that but might have done; can't remember question!
    9d) - I agree - the wavelengths would decrease, for 2 marks I think a statement needs to be made about cooling + expansion of universe + relative reduction in frequency of the waves to microwaves - thus you would expect further decrease in wavelength

    Based on this, pretty confident i got at least 50/60 - which should be A*. thanks a lot!
    The wavelength of CMBR will increased I checked it with my physics teacher and to be honest,this unofficial mark scheme is very poor most of it is wrong,from what I have read so far-The mirror is tilted so it is virtual all images produced in a mirror are virtual.
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    (Original post by ThatSameer)
    1c - I and my friends did light
    and for 7b its the radiowaves can diffract, not refract

    Otherwise i'd say pretty accurate mark scheme
    Light is correct. And well corrected, I meant diffracted.
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    (Original post by ThatSameer)
    1c - I and my friends did light
    and for 7b its the radiowaves can diffract, not refract

    Otherwise i'd say pretty accurate mark scheme
    Its not very accurate and I am sick of trying to correct the errors in it
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    (Original post by walkerbusinessfood)
    Very good!
    only issues: was motor gravitational or kinetic? it clearly converts to movement energy but would either be accepted as mark?
    5a) - this involved condensation so particle answer may not be correct; i am not sure.
    6b) - virtual - rays of light do not merge where they appear
    8c) - what was the question - don't think i put that but might have done; can't remember question!
    9d) - I agree - the wavelengths would decrease, for 2 marks I think a statement needs to be made about cooling + expansion of universe + relative reduction in frequency of the waves to microwaves - thus you would expect further decrease in wavelength

    Based on this, pretty confident i got at least 50/60 - which should be A*. thanks a lot!
    Because the load has to be lifted, I think the motor does have a job of raising the the load which gravitational potential energy. Kinetic in my opinion will also be accepted.

    Condensation does involve particles whereas a vaccum does not.

    The virtual question did catch me out. There could be several answers in my opinon for example, the image is a reflected image and therefore will not be the exact same.

    Question 8c?

    The last question was worth 2 marks. One for the stating the size of the waves and one for the reason. A basic description in my opinon would be enough.

    Good luck!
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    (Original post by ThatSameer)
    Also 1a is it's matt black AND metal as stated in the question. Matt black is good absorber and emitter and metal is a good conductor. 2 Mark question required 2 specs
    Yes that would be accepted. Other reasons such as the surface area of the stove increased the rate of energy tranfer.
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    I thought the exam was fine! really happy with the topics that came up<3


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    (Original post by ThatPerson)
    I think you mixed up the frequency question with the Specific heat capacity one.
    Yes, the answer is meant to be 1,200,000 Hz and the answer for SHC is the 2 million one. Thanks!
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    (Original post by Dalek1099)
    Its not very accurate and I am sick of trying to correct the errors in it
    I have stated above the mark scheme that there are many wrong answers but I have tried thinking of all of the questions on the paper in my head and figuring out what the answers were. I made the mark scheme within 15 mins.
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    (Original post by popburrow)
    Because the load has to be lifted, I think the motor does have a job of raising the the load which gravitational potential energy. Kinetic in my opinion will also be accepted.

    Condensation does involve particles whereas a vaccum does not.

    The virtual question did catch me out. There could be several answers in my opinon for example, the image is a reflected image and therefore will not be the exact same.

    Question 8c?

    The last question was worth 2 marks. One for the stating the size of the waves and one for the reason. A basic description in my opinon would be enough.

    Good luck!
    This needs correcting-a) Light ray drawn from the bulb to the mirror and into the persons eye.-it is not as simple as this-8mins48seconds is an example,with a person.

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