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

Summerdays
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#841
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What do you guys think the grade boundaries will be like?
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Mikkels88
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#842
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(Original post by bear54)
Didn't it say at the beginning of the ball question that is was neutral?
yeh but then it got charged, hence why it was attracted to the negative plate and so there was an extension

for grade boundaries, absolutely no idea :/ that was easier than the january paper (only cus of its section C to be fair) so maybe 75-80 for an A
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Summerdays
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#843
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(Original post by Mikkels88)
yeh but then it got charged, hence why it was attracted to the negative plate and so there was an extension

for grade boundaries, absolutely no idea :/ that was easier than the january paper (only cus of its section C to be fair) so maybe 75-80 for an A
Oh my, I hope not. This was MUCH harder than Jun 2010, so I am not sure. Maybe 68?
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Birkatron
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#844
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oh dear i got 9x10^7 for the electrons one?
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jimmeh
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#845
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(Original post by arianex)
I reasoned that since radioactive decay = random process, the number of nuclei we calculated that corresponded to the measured activity (that was given to us) would be a minimum - simply because we COULD have more nuclei present that just weren't decaying, therefore still giving us that same measured activity

EDIT// Well, I remember explaining it better in the exam. XD
Isn't it just that not all decaying nuclei are actually detected, so there are actually several other nuclei decaying, but the detector isn't pointing at them...
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Mikkels88
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#846
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(Original post by Summerdays)
Oh my, I hope not. This was MUCH harder than Jun 2010, so I am not sure. Maybe 68?
oh phew, i dont think i did june 2010 or cant remember it anyways so idk


(Original post by jimmeh)
Isn't it just that not all decaying nuclei are actually detected, so there are actually several other nuclei decaying, but the detector isn't pointing at them...
that would have been a good idea... damn
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Summerdays
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#847
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(Original post by jimmeh)
Isn't it just that not all decaying nuclei are actually detected, so there are actually several other nuclei decaying, but the detector isn't pointing at them...
Such an easy answer that slipped my mind. Damn
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Birkatron
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#848
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(Original post by Summerdays)
Such an easy answer that slipped my mind. Damn
oops went on a random babble about A=-lambaN and all that malarky :rolleyes:
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Summerdays
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(Original post by Birkatron)
oops went on a random babble about A=-lambaN and all that malarky :rolleyes:
So did I I said that the activity mut have been greater in the past haha
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stuffedfigs
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(Original post by Birkatron)
That wasn't too bad! :P For the radioactive people one i got 435, for the flux one did anybody get 7.1x10^-4wb?? and the 1.8x10^-3 for emf?? also the beta one i put it ionises the air in the gap so postive ions give the sphere positive charge so it moves downwards, that was on a past paper the same question 0.0, for the uranium thingy i got 1024kg?? ring any bells, also the prerelease what did people put for the very last question?? the picked some weird things to ask !!!
Flux Density = 0.7 T
I got 1.7x10^-4wb =/
Diameter was 1.8x10^-2 => Radius = 0.9x10^-2
Area= pi x radius^2

Flux= 0.7 x Area = 1.7x10^-4Wb
If I'm wrong oh well, I think I've done okay overall.
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Summerdays
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#851
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(Original post by stuffedfigs)
Flux Density = 0.7 T
I got 1.7x10^-4wb =/
Diameter was 1.8x10^-2 => Radius = 0.9x10^-2
Area= pi x radius^2

Flux= 0.7 x Area = 1.7x10^-4Wb
If I'm wrong oh well, I think I've done okay overall.
Oh crap... it said diameter? Damn, such a newb
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stuffedfigs
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#852
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(Original post by Summerdays)
Oh crap... it said diameter? Damn, such a newb
Yeah I read it and went "CHEEKY OCR, not letting you get away with that"
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jimmeh
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#853
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(Original post by stuffedfigs)
Yeah I read it and went "CHEEKY OCR, not letting you get away with that"
I did that, and then still fell for it. Not one of my finest moments, I have to admit...

Spotted my mistake when checking though! Felt like such a great moral victory...
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Summerdays
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#854
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(Original post by stuffedfigs)
Yeah I read it and went "CHEEKY OCR, not letting you get away with that"
SO ANNOYED. Urgh, that's what happens when you are reading really fast I have feeling that the two marks come from identying that 1/4piD^2 = area. Urgh. I did write that flux = BA though
Last edited by Summerdays; 7 years ago
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Geekchic17
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#855
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so did we decide grade boundaries are gonna be low for this paper?
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Summerdays
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#856
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(Original post by Geekchic17)
so did we decide grade boundaries are gonna be low for this paper?
I hope so. I feel really ashamed
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stuffedfigs
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#857
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Even though I screwed up a lot, it was a very fair paper, I think the same grade boundaries or higher than Jan 11.
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ChicharitoH
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(Original post by stuffedfigs)
Yeah I read it and went "CHEEKY OCR, not letting you get away with that"
I can just imagine someone literally shouting that in the exam
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arianex
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#859
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(Original post by jimmeh)
Isn't it just that not all decaying nuclei are actually detected, so there are actually several other nuclei decaying, but the detector isn't pointing at them...
They didn't mention a detector at all in that Q, just said that "the activity of the sample is xxx." But I suppose you could reason it that way...
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Geekchic17
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#860
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(Original post by stuffedfigs)
Even though I screwed up a lot, it was a very fair paper, I think the same grade boundaries or higher than Jan 11.
oww, what were they for jan11? around 80?
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