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AQA Physics PHYA4 - Thursday 11th June 2015 [Exam Discussion Thread] Watch

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    why is field strength 1560 and not 1875?
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    (Original post by chughes17)
    why is field strength 1560 and not 1875?
    Potential was 625V and r was 0.4m. E=V/r gives 1560 Vm^-1


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    (Original post by CD223)
    Potential was 625V and r was 0.4m. E=V/r gives 1560 Vm^-1


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    1/0.4=2.5 on the graph right? I might be being stupid but i'm reading it as 750 for V?

    edit: that's for 3 lmao how stupid. 1 mark or 0?
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    (Original post by CD223)
    Potential was 625V and r was 0.4m. E=V/r gives 1560 Vm^-1

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    shouldnt it be minus?
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    I managed to get the paper today, would anyone like me to post pictures of any pages/questions?
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    (Original post by CD223)
    Potential was 625V and r was 0.4m. E=V/r gives 1560 Vm^-1


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    Why can we not use the electric field formula for a point charge?


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    (Original post by TashJacobs)
    I managed to get the paper today, would anyone like me to post pictures of any pages/questions?
    Would be great if you could upload the multi choice part!
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    (Original post by TashJacobs)
    I managed to get the paper today, would anyone like me to post pictures of any pages/questions?
    Possible to take pictures of the Multiple Choice Section? Kind of find it hard to remember which answer I put down when I do not know the other three options that were available (trying to check what I put down against the mark scheme). Thanks!
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    (Original post by Salt and Peppa)
    Possible to take pictures of the Multiple Choice Section? Kind of find it hard to remember which answer I put down when I do not know the other three options that were available (trying to check what I put down against the mark scheme). Thanks!
    He did upload them, if the link is still available


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    (Original post by Vincent Song)
    shouldnt it be minus?
    I suppose it should yes, although I'm not sure whether that will be a marking point.


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    (Original post by CD223)
    I suppose it should yes, although I'm not sure whether that will be a marking point.


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    I used the electric field strength equation and I substituted the value of Q ,which was negative, in that equation and then I got -1560.
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    (Original post by Vincent Song)
    I used the electric field strength equation and I substituted the value of Q ,which was negative, in that equation and then I got -1560.
    Damn, which charge did you use??

    Edit: sorry, did you use the field strength for a point charge?

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    (Original post by Mehrdad jafari)
    Damn, which charge did you use??

    Edit: sorry, did you use the field strength for a point charge?

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    -27.8nC if that helps.
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    How fussy are examiners on minus signs? Neither my electric field strength nor work done was negative :/


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    (Original post by CD223)
    How fussy are examiners on minus signs? Neither my electric field strength nor work done was negative :/


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    I don't think if mine was either . If in the previous past papers the minus sign is in a bracket then the mark is not deducted


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    (Original post by Vincent Song)
    -27.8nC if that helps.
    Sorry, where did you get that?
    Edit: i got it, but i used the electric field formula for a point charge which gave me a different answer

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    (Original post by CD223)
    How fussy are examiners on minus signs? Neither my electric field strength nor work done was negative :/


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    The work done should be positive I think.
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    (Original post by Vincent Song)
    The work done should be positive I think.
    Oh really? I'm still unsure. To be honest I guess the numerical answer being right is the main thing.


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    The work done should be positive because it was the work done on a positive (60nC) charge
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    (Original post by Mehrdad jafari)
    Sorry, where did you get that?
    Edit: i got it, but i used the electric field formula for a point charge which gave me a different answer

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    .
    I got that value in 2c(i). Which formula? Is it E=Q/(4pie sth r^2)?
 
 
 
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