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ANSWERS: OCR Physics B(Advancing Physics) G491~ 20th May 2014~ AS Physics Watch

  • View Poll Results: Opinion of the paper
    Hard
    67.07%
    Medium
    10.98%
    Easy
    3.66%
    >55
    7.32%
    50-45
    14.63%
    44-49
    14.63%
    40-43
    10.98%
    35-39
    15.85%
    30-34
    9.76%
    25-29
    3.66%
    20-24
    4.88%
    <24
    2.44%
    I managed to finish all of the paper and check
    13.41%
    I managed to finish the paper but didn't check
    26.83%
    I missed off a few of the questions
    37.80%
    I missed >half of the questions
    3.66%

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    The resistance of the LDR... anyone else get 463.2 ohms!?
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    (Original post by Minecraft27)
    The resistance of the LDR... anyone else get 463.2 ohms!?
    473, here.
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    (Original post by Rizi0808)
    I took this paper without revision so i was going to find it impossible either way, but some of the further maths people in my class (the type who took as level maths modules a year early and got 100 ums) said it was a hard paper, harder than any of the past papers, if that makes anyone feel better... Any guesses at what an A would be??
    42?
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    14
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    (Original post by Shady23)
    See thats what I don't get, that paper with the low grade boundary was 100 times easier than this paper :'(
    So hopefully the grade boundaries for this paper are 100 times lower than that!
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    (Original post by Clai)
    Yeah in fairness the questions themselves weren't super hard, but the amount they expect you to do in one hour is ridiculous. Besides, having a lot of time pressure kind of equates to being a hard paper anyway, as people will drop marks.
    Hmmm I guess so, it was harder than stuff like m2 for mei, but then the maths is the ez bit
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    (Original post by Clai)
    I think it just depends on the answer you got to the previous question. I used my rounded value and got 3000kg, but to be honest 2000kg is better as it's closer at the very least...

    I just said it's comparable to 2400kg because they have the same order of magnitude
    Oh right yeah it should be fine then I used the value they gave to work it out
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    (Original post by Robbo54)
    473, here.
    Did you get that through

    V(out) = R1/(R1+R2) +V(s) ?
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    (Original post by Minecraft27)
    The resistance of the LDR... anyone else get 463.2 ohms!?
    I think I got the same as you. Rounded it to 463 Ohms though.

    And yeah I used:
    V(out) = R1/(R1+R2) +V(s)
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    (Original post by Clai)
    So hopefully the grade boundaries for this paper are 100 times lower than that!
    I wish! I'd probably still get a C or something somehow LOL
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    (Original post by Minecraft27)
    Did you get that through

    V(out) = R1/(R1+R2) +V(s) ?
    I use v1/v2 = r1/r2.

    I found the voltage at 1000 lux from the graph. Then 6 - LDR voltage to get the voltage of the fixed resistor.

    After that I re-arranged the formula to get R.
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    I love how on the WJEC thread I'm hearing things about how the paper was so easy that the grade boundaries will be high

    Why did my teachers choose this board?
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    (Original post by mynamewontfit)
    42?
    Nope, reckon it's lower. The 2010 paper that has a boundary of 35 for an A was much easier.
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    What did everyone get for the conductivity of graphene?
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    Something of the order 10^-7 ?
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    (Original post by kalios)
    What did everyone get for the conductivity of graphene?
    Something to the power of 17
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    Was the one about justifying the image length 4.76 or 5.26? I'm sure the question said 5% over...
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    The frequency of the wave on the second question. What did people get roughly?
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    (Original post by JackArch)
    The frequency of the wave on the second question. What did people get roughly?
    275 Hz
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    (Original post by Clai)
    I got the same as you asides from density - I think you're right, but the fact they said charge carrier density threw me. Charge carries are usually electrons so I thought maybe as electrons have no/negligible mass it would be m^-3 only?

    But I'm probably overthinking. Density is mass per unit volume.
    Electrons have a mass of 9.11*10^-31 or somewhere close to that. I know this since I do the A2 part of this OCR course.

    I got the resistance at around 460-470 ohms on the potential divider question; I can't remember exactly.
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    (Original post by CrystalPlanet)
    Electrons have a mass of 9.11*10^-31 or somewhere close to that. I know this since I do the A2 part of this OCR course.

    I got the resistance at around 460-470 ohms on the potential divider question; I can't remember exactly.
    Surely, though, the charge carrier density refers to the number of charge carriers, rather than their mass? Wikipedia (unreliable, I know) says m^-3.
 
 
 
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