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PHYA1 - Physics Unit 1 Exam - 24th May 2011 watch

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    (Original post by amoo94)
    so i'd get the mark for just saying antistrange?
    Well I can't remember what the exact question was, but if it specified the particle (i.e. K+) then you'd have to specify either strange or antistrange quark (depending on which one it is), but I'm not sure if it did as I thought it was just asking for a general reason (i.e. for all Kaons) so in that case the answer would just be strange quark or strange/antistrange quark, but not antistrange on its own.
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    (Original post by melon 314)
    i put strangeness is only conserved in the strong interaction for that question didn;t have a clue guessing i won't be getting any marks for that
    I put that too, and that other particles conserve all their properties in the weak interaction unlike strange particles
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    I feel like it went quite well

    Besides the vertical line oscilloscope and the why does terminal pd decrease, it was straightforward.
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    (Original post by Limitless)
    Which direction was the W+ boson I put and arrow pointing left.
    Right I think? going away from the neutron.

    Yes it is I've just checked in my book. W+ going right, though I'm sure you may have been able to put a W- going left.
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    (Original post by Limitless)
    Which direction was the W+ boson I put and arrow pointing left.
    It was too the right, a W- boson to the left would have been correct though as it is the same as a W+ to the right
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    (Original post by anil10100)
    Yeah for negligible resistance I drew the line y=1.52.
    So I got the EMF as 1.52.
    I got resistance as the negative gradient so 0.453, rounded to 0.45.
    The line B, I put as having twice the gradient as internal resistance doubled. So the gradient was -0.9 and y-intercept remains 1.52.

    For the last question I got overall resistance as 5Ohms (10/2).
    Then the next bit was just resolving the 3Ohm resistors until it equalled 5Ohms.
    For the last 2 I got, 1.3A(2sf) and 2V although I'm unsure on these.

    The decay was electron capture, Feynman diagram had a W+ boson, neutron, and neutrino.

    The second out of the two reactions was impossible as lepton number wasn't conserved (0--> -2)

    Unsure why the terminal potential difference increased as amps increased.

    Two baryons: neutron & proton.

    Strange particles have strange quarks.

    First oscilloscope trace was a dot 2 boxes above original.
    Vertical line because time base was off so no horizontal movement, and it's moving up and down so fast it appears a vertical line.

    6 marker was describing excitation then deexcitation, and explaining how the lines were discrete because of only certain wavelengths therefore frequencies therefore energy were possible as only certain energy photons can be emitted as there are only discrete energy levels the electron can de-excite through.

    S'all I remember, I'm open to correction, hope it helps
    *Decreased

    And I wasn't very good at explaining it, but as the terminal PD decreases the Lost PD in the cell increases, and since the resistance in the cell is constant, if PD increases in the cell, the current must increase aswell to keep the resistance the same (because R=V/I).
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    Really worried about exam now.

    I have messed up the circuit question.
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    (Original post by anil10100)
    Unsure why the terminal potential difference increased as amps increased.
    That battery gives energy per unit charge (Joules/Coulomb). Increasing the current means that there are more coulombs of charge flowing through each second, therefore more energy is given (Joules/Coulomb -> Joules/Coulomb*100 or so..). This means that the terminal voltage decreases as more voltage is needed to drive the coulombs of charge around the circuit with the same joules/coulomb.

    Hope that makes sense.
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    can someone post the exam paper please
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    (Original post by hwalker37)
    It was too the right, a W- boson to the left would have been correct though as it is the same as a W+ to the right
    Oops.
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    (Original post by Limitless)
    It was strange quark.
    You might get the mark for anti strange but I think it was asking generally not specifically. So a particle is strange if it contains a strange quark.
    I thought about putting strange quark, in the end i thought that was too easy so i put that strange particles include pie mesons in their decay
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    (Original post by Limitless)
    Oops.
    I shouldn't worry, only 1 mark lost
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    What did people get for the specific charge of the helium/alpha particle?
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    (Original post by hwalker37)
    I shouldn't worry, only 1 mark lost
    A mark here a mark there it adds up
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    (Original post by A level Az)
    What did people get for the specific charge of the helium/alpha particle?
    4.79 * 10^7 or something
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    I found the exam better than some years. There was no 'design an experiment' question which I was glad about, because I suck at those. Disappointed there was nothing on the photoelectric effect.

    Overall I'd say it was an average paper, no easier or more difficult than any others. One or two of the questions seemed to be worded a little strangely though, including the 'strangeness' question. xD
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    (Original post by Limitless)
    A mark here a mark there it adds up
    ^This
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    (Original post by A level Az)
    What did people get for the specific charge of the helium/alpha particle?
    Something Big haha I just did 2 x charge of proton divided by 4 x mass of nucleons
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    (Original post by A level Az)
    What did people get for the specific charge of the helium/alpha particle?
    4.somthing X10^7 Ckg-1
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    (Original post by Naum)
    4.79 * 10^7 or something
    I Got this too.
 
 
 
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