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

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    What did everyone get for the field strength? Was it right just to do the radial field strength formula and the use the Q=60nC and r=0.4?
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    (Original post by ubisoft)
    Flopped that badly lol. So happy I have a good AS mark
    What did you drop marks on?


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    (Original post by ubisoft)
    131 degrees anywhere?
    Yep, people are saying that rather consistently. 130/131 different degrees of significant figures though. Probably won't effect the mark at all.
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    (Original post by SuperMushroom)
    yep
    Yesss I need every mark i can lol, did you use BANwsinwt anywhere and get like 0.06 i think?
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    (Original post by jkrolling12)
    Yeah same here, apparently there were two charges involved though? Can anyone remember the exact situation of the question?
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    unofficial markscheme?
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    (Original post by CD223)
    What did you drop marks on?


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    everything, didn't revise enough, was too focused on my maths exams. Only wrote a line for 6 marker.

    wbu?
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    What was the correct answer to why it doesn't reach 1.4m? I put there is air resistance resisting the vertical motion and also energy is lost in the circuit due to resistance
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    (Original post by chizz1889)
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    ooohhh Thank you soo much... i thought i completely flopped this Q but it was just me using r^2 for potential but i am pretty sure i got x10^-5 in the exam.
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    (Original post by SuperMushroom)
    yep
    how did you do that question i did v/r which gives the angular speed in radians (i got something like 5 radians per second) then converted it into degrees and got like 340 degrees. Also i checked my answer by finding the percentage of the circumference it would move if the circumference was a straight line and then found the angle from this
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    (Original post by dominicwild)
    Yep, people are saying that rather consistently. 130/131 different degrees of significant figures though. Probably won't effect the mark at all.
    Nice.

    did you get 4R on mc anywhere? the 2 spheres with radius R
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    (Original post by salicional)
    The first part of the question used a 150Ω resistor, and the second part a 300,000Ω resistor. This lead to a graph that could not be drawn accurately, as it had to start at 1/2000th of the height of the original line! Clearly they missed a 'kilo' off the 150Ω, or added one in on the 300kΩ
    I noticed that, just drew it much lower down (below half fwiw) and presumed it wasn't a relative scale, even though it must be or the first graph wouldn't be right haha. Yeah, stupid question.
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    (Original post by JizzaStanger)
    It would depend on whether they asked for the change in the number of electrons or the total number of electrons. I think the change would be half but the total number wouldn't be.

    The fact that one of the choices was arrived at by halving Q worries me though, because halving Q is something that you would forget to do rather than do accidentally, and so if you weren't meant to halve Q then it's unlikely they would have put it as an option :/
    Oh well, only 1 mark
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    lol wait for the Q = 30nC question you didn't have to do any fancy stuff all you needed was to find the PD from the graph using the r values given - so you get 750V.

    Used W = QV with the 60nC charge and thats the work done...it was only like a 2/3 mark question
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    (Original post by DanielWall96)
    how did you do that question i did v/r which gives the angular speed in radians (i got something like 5 radians per second) then converted it into degrees and got like 340 degrees. Also i checked my answer by finding the percentage of the circumference it would move if the circumference was a straight line and then found the angle from this
    You just multiply the rad/s by the time, then change it into degrees
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    (Original post by ubisoft)
    Yesss I need every mark i can lol, did you use BANwsinwt anywhere and get like 0.06 i think?
    I used that equation but can't remember my answer. I thought they gave you the time period for 50 full circles (100) so after finding T I forgot to halve it even though I halved the value for f when subsituing 2nf!!! Stupid me!!!
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    (Original post by ubisoft)
    Nice.

    did you get 4R on mc anywhere? the 2 spheres with radius R
    I did. Looks like you didn't flop!


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    For the capacitor graph, was it above or below their original curve?
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    (Original post by Kennethm)
    lol wait for the Q = 30nC question you didn't have to do any fancy stuff all you needed was to find the PD from the graph using the r values given - so you get 750V.

    Used W = QV with the 60nC charge and thats the work done...it was only like a 2/3 mark question
    Yeah that's what I did lol.


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    Amanzz! Hey, hmmm. I agree with the other guys answer I think, smaller reduction in velocity/deceleration is less for given drag force etc. How did you find the paper?
 
 
 
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