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# OCR PHYSICS B G495~ 18th June 2015 AM ~ A2 Physics watch

1. (Original post by Minecraft27)
I got N to be 2.4x10^9 or something.

Anyone else get a resolution of 5.2x10^-7 and 30,000 lenses covering the eye?
Those first two numbers ring a bell, i definitely got something x10^9 for N. That many air particles seems a lot though for a 'vacuum.'
2. (Original post by Minecraft27)
I got N to be 2.4x10^9 or something.

Anyone else get a resolution of 5.2x10^-7 and 30,000 lenses covering the eye?
I got something like that

Something like that

Umm....maybe a bit less? I can't remember though....it was a large number any way

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3. For one of the 1 mark motor question did anyone do BAN to find flux linkage?
4. (Original post by STATER)
For one of the 1 mark motor question did anyone do BAN to find flux linkage?
I did BA....
Then BAN/0.2 at the top of the next page
Bugger

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5. (Original post by Aeglor)
I got about 22000, did it assuming there were 36 lenses per square 100m^-6... might have been more if you used a circle. Got the same resolution.
I got 30,000 by doing it the LONG way, with pi-r-squared and all, using the resolution that I got in the previous question, counting the eyes in the picture etc. After about a 500-step calc for 2 marks, I got 30000.
6. Low grade boundaries by the sounds of things then

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7. What exactly were they asking for in question 3 (the one about fields that had a straight line graph)?
I said the field was uniform shown by the straight line through the origin, and did two calculations which ended up as 4.2x10^3 and 4.3x10^3. Really was unsure what to do tbh.
8. (Original post by falconinni)
Those first two numbers ring a bell, i definitely got something x10^9 for N. That many air particles seems a lot though for a 'vacuum.'
Considering 1 mole of gas would be 6x10^23, one billion molecules per cubic centimetre is next to nothing.
9. (Original post by Rhetorical Hips)
Low grade boundaries by the sounds of things then

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Was the first one BA or BAN?
For the first one

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10. Guys, there are 100 x 100 x 100 centimetres cubes in one metre cubed right?

Somehow I screwed it up by saying there were 100 x 100 centimetres cubed in one metre cubed 😕

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11. (Original post by STATER)
What exactly were they asking for in question 3 (the one about fields that had a straight line graph)?
I said the field was uniform shown by the straight line through the origin, and did two calculations which ended up as 4.2x10^3 and 4.3x10^3. Really was unsure what to do tbh.
I wrote V and m were directly proportional therefore it was uniform etc.
12. (Original post by Minecraft27)
I wrote V and m were directly proportional therefore it was uniform etc.
Yes son. Did you your constant come out the same though?
13. Any unofficial ms?
14. (Original post by Rhetorical Hips)
Guys, there are 100 x 100 x 100 centimetres cubes in one metre cubed right?

Somehow I screwed it up by saying there were 100 x 100 centimetres cubed in one metre cubed 😕

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Yes, it was 100 x 100 x 100.

For the 4-marker about the rotor jamming, I wrote about resistance and stuff like that, filled the page with BS. Hope to get at least 2 for trying.

This paper was not too difficult. I reckon about 72 for an A.
15. Don't remember the question, something to do with a rotor in a stator where something increases (might have been potential difference but I'm not sure). It asks what happens to the speed of rotations? I put that although the force on the rotor will increase, the speed of rotations does not due to the fact that the question stated that the current remains the same and I figured this meant that the poles don't switch any quicker so it can't spin any faster... Does anyone agree/disagree? And does anyone actually remember the question properly?
16. (Original post by Minecraft27)

This paper was not too difficult. I reckon about 72 for an A.
Last year it was 74 though. Do you think this one was harder overall?
17. I got C for question 5 about the amps and voltage of the second coil (0.36A, 6V).

Anyone else get 16.8 for magnification and 11.2 Dioptres? My friend got 188 dioptres... which one is correct?
18. (Original post by Minecraft27)
I got C for question 5 about the amps and voltage of the second coil (0.36A, 6V).

Anyone else get 16.8 for magnification and 11.2 Dioptres? My friend got 188 dioptres... which one is correct?
Yes
Yes
I got x200 too
19. (Original post by Minecraft27)
I got C for question 5 about the amps and voltage of the second coil (0.36A, 6V).

Anyone else get 16.8 for magnification and 11.2 Dioptres? My friend got 188 dioptres... which one is correct?
I got 200 Dioptre. v and u were given in milimetres so it seemed right at the time.

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