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

1. aha no worries, I am by no means asserting I am right, just thought it would be more constructive to post what I actually thought the answer would be in the exam. The greatest thanks go to you for your original set of answers, you did far more work than I typing it all up, for most of the questions I just blasted through and assumed that if our answers matched, they were right, however over the weekend I may again go through the paper and not look at your answers, and see what I get, just to make sure it's all gooooooood
2. (Original post by Summerdays)
Due to a 12eV electron colliding inelastically with the hydrogen atom, the answer is based on the assumption that the electron, that is bound to the nucleus of the hydrogen atom, gains as much energy as possible. We also assume that the electron was in the ground state, before the collision took place. So -13.6eV + 12eV = -1.6eV. But this means that the electron (bound to the hydrogen nucleus) has moved to the energy level that is equal to -3.4eV (there wasn't enough energy for the electron to move to the energy level "-1.5eV", because this energy level is less negative than -1.6eV)
This means that 3.4eV-1.6eV = 1.8eV is left as kinetic energy, for the electron.
Ok thanks, seems like it should be 2 marks at least for that, maybe it's just me
3. (Original post by bear54)
Ok thanks, seems like it should be 2 marks at least for that, maybe it's just me
It's OCR B...

4. what are those answers for? the long list that Summerdays and someone else (Sorry forgot the username :L ) did, where are the questions?
5. Is there a copy of the advance notice paper anywhere online/could someone upload theirs?
6. Also, all the possible questions above, is that from teachers or OCR?
7. (Original post by SteveScott)
Is there a copy of the advance notice paper anywhere online/could someone upload theirs?
It's on the OCR site
8. (Original post by 41jms)
what are those answers for? the long list that Summerdays and someone else (Sorry forgot the username :L ) did, where are the questions?
I posted them earlier in the thread, they are incredibly useful.

http://www.school-portal.co.uk/Group...urceID=3903515
9. (Original post by JoeCarr)
I know right, big love to whoever produced it at whatever school it was, it's perfect but we now just need to work through it with answers, I have an English Lit exam tomorrow but can start putting my answers up in the afternoon.
my teacher made them questions hahaha!

the official answers he put up are here:

http://www.skillspace.com/DIGITALLOC...SWERS%20v2.pdf
10. Would anything from Unit 4, that as a result wouldn't come under Unit 5 topics, be likely to come up in the exam?
11. (Original post by R0BMAN)
Really nervous for this exam, its my toughest exam and the most important one. Out of 150UMS I only need 96 to get into Uni so long as I pass my other exams, which is only about 64/100 marks but still, im not good at Physics at all and some questions really bum me over. Still cant tackle any special relativity stuff and long answer questions are baaaddd.

Does anyone know any equations with voltage in them that you need to know, excluding the obvious like V=IR, P=V^2/R and P = I^2R.... would really be useful, thanks.
In the second section of this course you need to know these 4:

F = kQq/r^2
Electric potential energy = kQq/r (if it helps F is Newtons, r is m and J = Nm)
Electric field strength = kQ/r^2 (so electric field strength = F/q)
Potential different = kQ/r (so Volts = electric field strength x distance)

That last one is the volts one and from there Electric field strength = volts/distance is another they're likely to ask about.

Don't know of any other volt equations you need.
12. (Original post by Mikkels88)
my teacher made them questions hahaha!

the official answers he put up are here:

http://www.skillspace.com/DIGITALLOC...SWERS%20v2.pdf
oh wow, tell him he is a hero to us all, and thank you so much for the 'official' answers!

repped
13. I knew we had to take into account the distance doubling when the mirror was moved, me and my friend were just not 100% and this has cleared it up where our teacher failed, again cheers!
14. i think you can take those answers as God's word cus this guy is literally a physics robot
15. (Original post by Mikkels88)
i think you can take those answers as God's word cus this guy is literally a physics robot
I got that impression from

' Consider a young, non-spinning
molten Earth. (This isn’t strictly
necessary for the argument – in
what follows even a solid Earth will
deform plastically over a long
enough time) The gravitational
force will try to pull all parts of the
planet as close as possible
together.
A stable spherical shape is formed
when the gravitational force on a
small element of volume is in equilibrium with the outward force
due to the pressure difference
across the element.
When the Earth is spinning then
the gravitational force on an
element in the equatorial plane
must be bigger than the force due
to the pressure difference so that
there is a resultant force on the
element towards the axis of
rotation to provide the centripetal
force for circular motion.
Hence the element moves
outwards to where the force due to
the pressure difference is smaller
than the gravitational force on the
element. Thus the equatorial
radius becomes greater and so the
so that volume is conserved'

O.o

But yeh this is perfect and i'm very impressed with the level of detail and attention he has put into this advance notice, last year we barely touched upon it and this year we spent maybe an hour, hour and a half max going through some vague questions that were nowhere near as good as these!
16. "Galileo claimed that he could measure time intervals with the water clock to one tenth of a pulse beat. Suppose that Galileo’s pulse rate was 70 beats per minute.
b) What is the uncertainty - in seconds - in Galileo’s time measurements ?"

If it was 70 per minute, why isn't it (70/60)/10? In the answer it's (60/70)/10
17. (Original post by Mikkels88)
i think you can take those answers as God's word cus this guy is literally a physics robot
Thank you for theses answers. They were REALLY helpful, and I will go over them today
18. (Original post by bear54)
"Galileo claimed that he could measure time intervals with the water clock to one tenth of a pulse beat. Suppose that Galileo’s pulse rate was 70 beats per minute.
b) What is the uncertainty - in seconds - in Galileo’s time measurements ?"

If it was 70 per minute, why isn't it (70/60)/10? In the answer it's (60/70)/10
Think of it this way, if a car drives over 3 speed bumps, in say 30m, you'd work the distance between each speed bump out as 30m/3 bumps, which is 10m per bump. This is the same with this, 60s (30m)/ 70 beats (3 bumps). Also, it might help to recognise that it is illogical to have each beat lasting over a second (70/60), if there are more beats than seconds.....

also, inb4 a smartass states that I am not taking into consideration the width of the speed bumps, they are negligible in this example, because I said so.....
19. (Original post by JoeCarr)
Think of it this way, if a car drives over 3 speed bumps, in say 30m, you'd work the distance between each speed bump out as 30m/3 bumps, which is 10m per bump. This is the same with this, 60s (30m)/ 70 beats (3 bumps). Also, it might help to recognise that it is illogical to have each beat lasting over a second (70/60), if there are more beats than seconds.....

also, inb4 a smartass states that I am not taking into consideration the width of the speed bumps, they are negligible in this example, because I said so.....
Ok thanks, I just always though 'per x' meant 'divided by x', like in percent, out of 100
20. (Original post by bear54)
Ok thanks, I just always though 'per x' meant 'divided by x', like in percent, out of 100
i did exactly what you did mate, but we worked out the number of beats per second, instead of how many seconds a beat was... so when he can measure it to one tenth of a beat, you want to know what one tenth of a beat is in seconds, which is the number of seconds PER BEAT, divided by 10.

I hate uncertainties.

also, check this out from the spec:
(Original post by spec)
For questions in Sections A and B of the examination paper based on the specification content below, synoptic assessment will involved those aspects of the AS course, and also the earlier A2 Unit G494, which are appropriate for the content specified in this unit.
yeh... the earlier unit.... top notch scheduling there OCR

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