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OCR PHYSICS B G491~ 19th May 2015 AM ~ AS Physics

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Original post by BongoBuddha
Yeah, I hope I get a method mark -I have made so many silly mistakes though
-only just finished in time,

Did anyone else struggle for time?


I didn't struggle for time a lot personally but that's only because I write quickly, I feel that the exam wasn't too bad, there have been worse past papers, but knowing me I probably only just got an E
Original post by thebigman98
yes i struggled for time, had to make a few last minute guesses and made silly mistakes, hopefully the grade boundaries are low, but people seemed to find it easy.


Thankgoodness Its not just me, hopefully it will be just 40 for an A or something like that (wishful thinking). Well toodaloo, must pop, I've got to revise C2 maths now for tomorow morning.
In the chirrup question I guessed that the average frequency was 2.5kHz? Guessed 3kHz at first but it seemed a bit too large? Let's hope they have that the mark scheme allows for some kind of range. I hate that they give us crudely drawn graphs and let us guess the numbers…
Original post by notrodash
In the chirrup question I guessed that the average frequency was 2.5kHz? Guessed 3kHz at first but it seemed a bit too large? Let's hope they have that the mark scheme allows for some kind of range. I hate that they give us crudely drawn graphs and let us guess the numbers…


They'll give you that, the mark scheme always has ranges for those types of questions

By the way, does anyone know when the mark scheme comes out?
Original post by Zain.chishty
magnification = the image size (i got 83 mm) / 270 pm * 99
you have to convert all the values in m.
for resolution i got = 270 pm * 99 / total pixels in the width of the image ( i think there were 500)

whered you get the 99 from
Original post by airborne454
whered you get the 99 from


Exactly
They just made it up


Posted from TSR Mobile
Did I get this completely wrong?

I measured 8 atoms in a row off of the picture to be about 1.7cm, and seeing as we know 1 atom was 270*10^-12, I divided them through to get magnification. I used SI units
Original post by Mutleybm1996
Exactly
They just made it up


Posted from TSR Mobile

I got around 83 atoms, since i measured the diameter to be 1mm, and the width to be 83mm
was the resolution mpixel-1 or mmpixel-1
Original post by RandomThrowaway
What did people get as the size of the video?


3.375 x 10^7 I think
Original post by CancerousProblem
yeah taht was what I put on my paper and I am really confused :confused: as to what I should have done. I put down 3.2 with that reasoning but now i have my doubts i think its 4.8


I put 4.8 because I just used the normal thin lens equation, but I strongly think that 3.2 is the right answer now because, as someone pointed out earlier, both distances are on the same side of the lens, and to achieve -0.8 curvature from -4 curvature, all you need to do is add 3.2 D.

Actually, tbh I just confused myself in typing that out...really not sure what the answer is... :/
Original post by CancerousProblem
**** I got 0.18m

I think the question tripped me up somewhere or I missed a zero on my calculator


I got 0.018 m, but I thought that it was an unrealistically small answer...can't say I know much about filaments, though...
Original post by Fandalf
Peeps, is it still possible for me to get an A overall if I say get a C in this? By e.g getting 100 ums in unit 2?


I know someone who got a C in Paper 1 last year and an A in Paper 2, and she got an A overall. Paper 2 is worth more than Paper 1, remember. Also, it probably depends on what you got for your coursework.
unofficial mark scheme?
Original post by yellownectarine
I got 0.018 m, but I thought that it was an unrealistically small answer...can't say I know much about filaments, though...


0.018m is 1.8cm - think of the size of a bulb and the filament inside of it seems likely. I got 0.018m and rounded it to 0.02 (I generally do 2dp or 3sf) do you think this will count against me? I had 0.018m in the working.
Original post by CancerousProblem
3.375 x 10^7 I think


Same
Unoffical mark scheme ?
Let's start the mark scheme?
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Wolfea
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Original post by ThatPerson2
0.018m is 1.8cm - think of the size of a bulb and the filament inside of it seems likely. I got 0.018m and rounded it to 0.02 (I generally do 2dp or 3sf) do you think this will count against me? I had 0.018m in the working.


It might count against you, but I doubt it: it depends on the examiner and mark scheme.
Original post by ThatPerson2
0.018m is 1.8cm - think of the size of a bulb and the filament inside of it seems likely. I got 0.018m and rounded it to 0.02 (I generally do 2dp or 3sf) do you think this will count against me? I had 0.018m in the working.


They usually like the answers to be to at least 2 significant figures

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