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

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Original post by STATER
I got 200 Dioptre. v and u were given in milimetres so it seemed right at the time.


I got 11.2 but I don't remember how.

EDIT: I did 0.089 as the focal length, as that was the length between the lens and the image.
(edited 8 years ago)
Why was it 6V and 0.36A?
Original post by kingofgames010
Why was it 6V and 0.36A?


If you actually did all the calculations that's what you get.

I did all the calcs for a 1 marker, because I get extra time in the exam.
(edited 8 years ago)
The focal length was 0.089m wasn't it? That was the distance between the lens and the image. Therefore the power would be 11.2 Dioptres, not 200.
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STATER
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Original post by Minecraft27


EDIT: I did 0.089 as the focal length, as that was the length between the lens and the image.


Isn't 0.089 the distance between lens and screen (projection) though? Focal length is a bit less.

I said v=0.089 and u= 0.008? (whatever the small distance was)

1/v = 1/u +1/f
1/f turned out as 200
(edited 8 years ago)
Original post by Minecraft27
If you actually did all the calculations that's what you get.

I did all the calcs for a 1 marker, because I get extra time in the exam.


I did the calculation and found 6V, but how did you get from that to Current?
Original post by kingofgames010
I did the calculation and found 6V, but how did you get from that to Current?


With current it's I2/I1 = N1/N2.

Maybe you did I1/I2 instead of I2/I1. VERY easy mistake to make.
Original post by Minecraft27
With current it's I2/I1 = N1/N2.

Maybe you did I1/I2 instead of I2/I1. VERY easy mistake to make.


**** yeah that's what. Ah well. Thanks anyway! What are most people predicting the A grade mark will be?
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STATER
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Original post by kingofgames010
**** yeah that's what. Ah well. Thanks anyway! What are most people predicting the A grade mark will be?


73-75
Original post by kingofgames010
**** yeah that's what. Ah well. Thanks anyway! What are most people predicting the A grade mark will be?


I predict about 72-74.
(edited 8 years ago)
Original post by Minecraft27
The focal length was 0.089m wasn't it? That was the distance between the lens and the image. Therefore the power would be 11.2 Dioptres, not 200.


I done that but it's wrong, that's calculating 1/v, when you should have used the lens equation 1/v=1/u+1/f to find out 1/f

but woooooooooooooooooo no more exams!!!!!!!!!!!! (until uni...)
for the final question i converted the potential energy into eV = 3.2*10^-14 and added this to 0.511*10^6 eV to get Etotal and divided by 0.511*10^6 eV as this was Erest. But my graphical calculator gave this of gamma equal to 1 :/ but then did a separate calculation and worked out v = 2.1*10^8 ms-1, is that correct? :/ how did you do it?
Reply 272
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Cowy97
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Original post by STATER
I got 200 Dioptre. v and u were given in milimetres so it seemed right at the time.


i also got 200D using 1/v=1/f+1/u
Original post by RealTime
I done that but it's wrong, that's calculating 1/v, when you should have used the lens equation 1/v=1/u+1/f to find out 1/f

but woooooooooooooooooo no more exams!!!!!!!!!!!! (until uni...)


so was it 200D ? ;/ also was it nucleon number that was not conserved in one of the questions because mass and charge were and i didn't even know what quark number is haha!! :/ what did you get the resolution of the flea image as?
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STATER
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Original post by HennersPD
v = 2.1*10^8 ms-1, is that correct? :/ how did you do it?


That is correct
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STATER
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Original post by HennersPD
so was it 200D ? ;/ also was it nucleon number that was not conserved in one of the questions because mass and charge were and i didn't even know what quark number is haha!! :/ what did you get the resolution of the flea image as?


Mass was not conserved since a gamma photon was released.
Original post by HennersPD
so was it 200D ? ;/ also was it nucleon number that was not conserved in one of the questions because mass and charge were and i didn't even know what quark number is haha!! :/ what did you get the resolution of the flea image as?


I can remember the resolution, although previously that 5.2x10^-7 m/pixel rings a bell

And I wirtten quark number not conserved because a proton or neutron decayed and yeah not much else reasoning to it, might wrong lol.

And yeah seems like it was 200D, guess i should have done more lens questions for revision lmao
Original post by HennersPD
for the final question i converted the potential energy into eV = 3.2*10^-14 and added this to 0.511*10^6 eV to get Etotal and divided by 0.511*10^6 eV as this was Erest. But my graphical calculator gave this of gamma equal to 1 :/ but then did a separate calculation and worked out v = 2.1*10^8 ms-1, is that correct? :/ how did you do it?


Yeah I think that's correct, I also got that too
Is anyone going to make a mark scheme? I can't remember many of the questions :redface:
(edited 8 years ago)
Did anyone else get 2312K for the temperature for 3N electrons per second? It took me forever!
Also now I'm worried that I didn't read it properly and can't remember if it wanted the increased temperature or how much it had increased by :s-smilie:

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