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

1. Any else get 1.8x10^-4 Wb for the flux value?
2. (Original post by Swindan)
Now I'm questioning my answer to the previous question too I ended up with something like 2.95^-11
I found the average binding energy of the two fragment nuclei.
Added this to the binding energy of uranium. And multiplied it by the number of nuclei and obviously 1.6x10^-19x1x10^6
3. (Original post by Swindan)
Now I'm questioning my answer to the previous question too I ended up with something like 2.95^-11
me too! pretty sure its right..
4. (Original post by Revolution is my Name)
Grade boundaries people! Similar to last June? (75 for A, 67 for B, 83 for 90)
I recon it will be <=70
5. (Original post by Summerdays)
I blagged it as well
I really didn't understand the question
Let's just pray for not-so-harsh grade boundaries now xD

Also, how did everyone fare on the very last Q where it asked us to *describe* how you would measure some lengths using method 2? Here's what I put:

- Time how long it takes with said standardized beam to travel the distance you want to measure (using the caesium standard)

- Since T = 1/f, you can find the frequency of said beam that way

- lambda = c/f so use it to find the wavelength of the beam...

- Multiply the wavelength by the time in seconds that you logged in earlier = distance measured?
6. im going to get off this thread now, i cant remember most of my answers! hope you all get what you need, good luck for results
7. (Original post by Summerdays)
I found the average binding energy of the two fragment nuclei.
Added this to the binding energy of uranium. And multiplied it by the number of nuclei and obviously 1.6x10^-19x1x10^6

don't think u need to find an average for binding energy... as long as you multiply the binding energy per nucleon by the number of nucleons then this will work out the correct ratios etc for you
8. (Original post by arianex)
Let's just pray for not-so-harsh grade boundaries now xD

Also, how did everyone fare on the very last Q where it asked us to *describe* how you would measure some lengths using method 2? Here's what I put:

- Time how long it takes with said standardized beam to travel the distance you want to measure (using the caesium standard)

- Since T = 1/f, you can find the frequency of said beam that way

- lambda = c/f so use it to find the wavelength of the beam...

- Multiply the wavelength by the time in seconds that you logged in earlier = distance measured?
I said something about finding the frequency by finding the number of wavelengths when the mirror moves a distance, d.
C is the EXACT value, in a vacuum.
The frequency of light IS the definition of one second.

I blagged it
9. (Original post by Swindan)
Now I'm questioning my answer to the previous question too I ended up with something like 2.95^-11
10. (Original post by kttt101)
don't think u need to find an average for binding energy... as long as you multiply the binding energy per nucleon by the number of nucleons then this will work out the correct ratios etc for you
I wasn't really sure how to do it. I used the CPG way of doing it: look at the right hand side of page 55.
11. (Original post by ejw93)
ditto d
12. (Original post by Summerdays)
I said something about finding the frequency by finding the number of nuclei when the mirror moves a distance, d.
C is the EXACT value, in a vacuum.
The frequency of light IS the definition of one second.

I blagged it
Number of nuclei? XD
13. For the phasors question, I guessed that decreasing the air density would cause the speed of light to increase, hence introducing a lag in OX (or whichever one it was) This would cause that phasor to rotate. Hence you get the detector changing from light to dark, at a fequency which I claimed would be proportional to the rate of decrease of density of air.
14. (Original post by arianex)
Number of nuclei? XD
I mean wavelengths. HAHA
15. (Original post by Summerdays)
I wasn't really sure how to do it. I used the CPG way of doing it: look at the right hand side of page 55.

The purple book? page 55 is Millikan's oil drop experiment?

Multiple the number of nucleons for each element by the binding energy per nucleon will give you the whole binding energy of the nucleus.. the difference in the total binding energy of the U235 and the sum of the binding energies of the other two nuclei is the energy released

thats how i did it anyway, if u got near enough 3 x whatever then either of us could be right lol
16. (Original post by kttt101)
The purple book? page 55 is Millikan's oil drop experiment?

Multiple the number of nucleons for each element by the binding energy per nucleon will give you the whole binding energy of the nucleus.. the difference in the total binding energy of the U235 and the sum of the binding energies of the other two nuclei is the energy released

thats how i did it anyway, if u got near enough 3 x whatever then either of us could be right lol
No, not the purple book - the one catered to A2 Physics (not jut OCR B.) There should be more than one method of doing it though, I think
17. (Original post by Summerdays)
No, not the purple book - the one catered to A2 Physics (not jut OCR B.) There should be more than one method of doing it though, I think

ah i see.. i dont have that lol :P

yeah yeah for sure
18. (Original post by kttt101)
ah i see.. i dont have that lol :P

yeah yeah for sure
How did you find it overall? For the calculate emf, did you do flux/given time, and said something about the gradiant constantly chaing?
19. did anyone put that the difference in speed of the two wavelengths due to the refraction would cause the superposition effect to break down?

i totally guessed that
20. (Original post by Summerdays)
How did you find it overall? For the calculate emf, did you do flux/given time, and said something about the gradiant constantly chaing?

it wasnt as bad as i thought it would be actually

yeah exactly that.. but i ended up dividing the emf by two... took a risk! if it turns out wrong it will only be a mark

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