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OCR Physics B G495 Field and Particle Pictures June 21st 2011 Exam Thread watch

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    (Original post by Rogercbinboy)
    Reckon saying "make the core fatter" would get the mark for the cross sectional area point?
    Probably since making it fatter would increase the cross-sectional area of the iron core! I don't know if they want the correct terminology though :/ Probably not because it was like Section A or B though
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    for the x-ray question did anyone get alot of people dying?!
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    (Original post by jimmeh)
    Increase permeance? Balls. Definitely read that wrong, could've sworn that it said increasing the flux...That's what you get for being confident :rolleyes:

    I put increasing the current and number of turns, but if it said increase the permeance, then those are definitely wrong!
    it said if the current and number of turns were kept the same so i cant see them awarding marks for that dude ... reading the question twice might of helped!
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    (Original post by Alex.Stevens)
    for the x-ray question did anyone get alot of people dying?!
    435 painful, agonising deaths.
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    (Original post by Unkempt_One)
    435 painful, agonising deaths.
    Dammit :/ I got 435 then divided by 100 for some reason :/ I thought you had to divide 3% by 100 to get 0.03 because 0.03 is like the proportion of people who would die per sievert
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    laminating the core doesnt increase the permeance, it increases the total flux... i think they were driving at larger area, shorter length or higher permeability material (they never said it was iron, so i said use an iron core)

    overall a good paper, a few OCR moments where you just go "WTF is that question asking?!" but mostly good.

    A few answers : 9 x 10^9 for the 1 sig fig number of electrons?
    speed for relativistic im hoping i put 450 x 10^6 odd, cus other people seem to have that lol...
    i got 4.4 people (so 4) for the cancer one... in 25 years that seemed pretty ok to me, but i still said unnecessary risk for the next bit etc

    last question, what the hell did they want? I talked about measuring the frequency of the laser, and cus speed of light is DEFINED as w/e and a second is DEFINED theres no error in those values, so you can get a very precise f and so a very precise lamda using v = f lamda... not sure how it really helps you measure distance tho :/ i basically just bull****ted hehe

    :bl:
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    (Original post by Larry777)
    Dammit :/ I got 435 then divided by 100 for some reason :/ I thought you had to divide 3% by 100 to get 0.03 because 0.03 is like the proportion of people who would die per sievert
    I GOT 17!!! ***t!! dont know how i got that if u all got 435....
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    also if anyone has a copy of paper / mark scheme i would love you so much
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    (Original post by Larry777)
    Dammit :/ I got 435 then divided by 100 for some reason :/ I thought you had to divide 3% by 100 to get 0.03 because 0.03 is like the proportion of people who would die per sievert
    You might be right actually, let me think about that for a minute.
    EDIT: Yep you're right, oh well.
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    (Original post by Alford)
    it said if the current and number of turns were kept the same so i cant see them awarding marks for that dude ... reading the question twice might of helped!
    Ahaa, I swear I read it twice! Need to get some new glasses or something ¬.¬
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    (Original post by Mikkels88)
    laminating the core doesnt increase the permeance, it increases the total flux... i think they were driving at larger area, shorter length or higher permeability material (they never said it was iron, so i said use an iron core)

    overall a good paper, a few OCR moments where you just go "WTF is that question asking?!" but mostly good.

    A few answers : 9 x 10^9 for the 1 sig fig number of electrons?
    speed for relativistic im hoping i put 450 x 10^6 odd, cus other people seem to have that lol...
    i got 4.4 people (so 4) for the cancer one... in 25 years that seemed pretty ok to me, but i still said unnecessary risk for the next bit etc

    last question, what the hell did they want? I talked about measuring the frequency of the laser, and cus speed of light is DEFINED as w/e and a second is DEFINED theres no error in those values, so you can get a very precise f and so a very precise lamda using v = f lamda... not sure how it really helps you measure distance tho :/ i basically just bull****ted hehe

    :bl:
    i got 4 people too
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    (Original post by Larry777)
    Dammit :/ I got 435 then divided by 100 for some reason :/ I thought you had to divide 3% by 100 to get 0.03 because 0.03 is like the proportion of people who would die per sievert
    Yeah, I got 435%, then divided by 100 which gave me 4 deaths...Most people I spoke to after got 4 too
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    (Original post by Alex.Stevens)
    did you manage to do it in the end?
    I tried finding the mass with E=mc^2, then using KE = 1/2 mv^2?! but V was something like 3.8x10^8
    In my last ditched attempt I set the relativistic factor (0.8 or something, right?) from E(tot)/E(rest) equal to the relativistic equation (the whole shabang with 1/(sqrt)(1-v^2/c^2) and attempted it from there with a minimal amount of luck... :/
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    (Original post by Alford)
    I GOT 17!!! ***t!! dont know how i got that if u all got 435....
    I got 17.4 too. What was the initial amount of people I can't remember? Because if it's in the thousands then 435 like other people are saying sounds too high to me, if the data is based on reality I don't think an x ray giving that much dangerous radiation would be allowed
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    (Original post by Zakky)
    I got 17.4 too. What was the initial amount of people I can't remember? Because if it's in the thousands then 435 like other people are saying sounds too high to me, if the data is based on reality I don't think an x ray giving that much dangerous radiation would be allowed
    You forgot to multiply by 25 for the number of years.
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    It was like 298000 people over 25 years so it think 435 people sounds reasonable.

    Also, does anybody know anything about grade boundaries or what total mark i need to get out of 600 to get a A?
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    A from 600 is 480, A* is 540, CW is out of 30 but worth 60 UMS so if your teacher gave you a mark overall for CW out of 30 just double it for your UMS hoping for at most 10-15 marks dropped on that, ideally under 10, A* physics would be nice
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    The answer is 4.35, end of.
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    (Original post by 5liam5)
    what total mark i need to get out of 600 to get a A?
    Always 480/600 for an A, but the raw marks needed to get that UMS is variable.
    What do people think for grade boundaries for this? Maybe similar to last year? 75 for an A, 67 for a B? (so 83 for 90%)
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    I got 4.35 people and rounded it up to 5. I hate those questions haha

    I was generally pretty happy with the paper, hopefully it will be the 2nd A for my durham offer
 
 
 
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