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

1. (Original post by vish.handa)
0.8cm as in 8 mm??? that seems quite large or do you mean 0.8mm? if so i got 1mm which is close to that ?
Your ruler can measure to 0.1 of a mm? I need one of those!

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2. (Original post by Mutleybm1996)
I didn't spot that
Might get some method marks for the formulae though

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but i was unsure because there was a faint circle surrounding the white spot which i thought would be the atom since the white spot at the centre implies nucleus and the atom is the circle surrounding that (from shells in chemistry) and that diameter was 08.cm? it sounds likes some people just measured the diameter of the white spot which was REALLY tiny so I fail to see how they worked it out from the image given as 2mm?! got the magnification as 3*10^7?? Anyone get similar?
3. (Original post by Mutleybm1996)
Your ruler can measure to 0.1 of a mm? I need one of those!

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ahahaha micrometer?? you never know
4. (Original post by HennersPD)
but i was unsure because there was a faint circle surrounding the white spot which i thought would be the atom since the white spot at the centre implies nucleus and the atom is the circle surrounding that (from shells in chemistry) and that diameter was 08.cm? it sounds likes some people just measured the diameter of the white spot which was REALLY tiny so I fail to see how they worked it out from the image given as 2mm?! got the magnification as 3*10^7?? Anyone get similar?
i got 3 *10^6
5. (Original post by Mutleybm1996)
If it wanted you to use 99 it would have said 99...........

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Yeah pretty sure you had to use 100. Saying <100 includes numbers such as 1, i don't think you'll get any marks if you use 1,2,3 etc
6. (Original post by Mutleybm1996)
I'm not sure measuring it was the right way to go to be honest especially if it's that ambiguous

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It told you to measure it, and all of the past papers include measuring it so you get cmpixel-1 then work out the resolution
7. (Original post by Mutleybm1996)
Yes
But it didn't say HOW MANY atoms

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if u used any number from 90 to 99 , the answer u'll get will approximately be 3.0 * 10^6 , and this is what u get if u measure the diameter of an individual atom on the image.
I am sure any body won't use one atom when the question says that the image contains just less than 100 atoms in the width
8. (Original post by Zain.chishty)
i got 3 *10^6
How??
9. (Original post by thebigman98)
It told you to measure it, and all of the past papers include measuring it so you get cmpixel-1 then work out the resolution
Not if some people used 2mm and others used 8mm

Then some people used different numbers of atoms and all sorts of things

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10. (Original post by Zain.chishty)
if u used any number from 90 to 99 , the answer u'll get will approximately be 3.0 * 10^6 , and this is what u get if u measure the diameter of an individual atom on the image.
I am sure any body won't use one atom when the question says that the image contains just less than 100 atoms in the width
I know it's not 1, I'm just saying <100 could be anything sensible from 10-99 for all we know

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11. Hey for the suitable metals microstructure question did you have to talk about alloying? i just talked about metallic structure :/
12. "What did anyone get for that question about bytes for the image? Was it something around 75000"

-i got 750,000
13. Has anyone made an unofficial mark scheme for this yet?
14. (Original post by BongoBuddha)
"What did anyone get for that question about bytes for the image? Was it something around 75000"

-i got 750,000
it was 75,000
15. (Original post by thebigman98)
it was 75,000
doh! there goes 2/3 more marks -oh well there's always nxt year
16. No. you were supposed to measure the image with a ruler, and divide that by the diameter of the atom.
17. (Original post by BongoBuddha)
doh! there goes 2/3 more marks -oh well there's always nxt year
dont worry you probably did the right sum just added a 0 on somewhere, you'll get method marks
18. I got that too!
(Original post by thebigman98)
it was 75,000
19. (Original post by thebigman98)
dont worry you probably did the right sum just added a 0 on somewhere, you'll get method marks
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?
20. (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 srtuggle for time?
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.

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