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

I didn't realise there was a feburary 11 exam, if anyone manages to get hold of it then that'd be great :P

Can I just ask, I need 50 UMS in this final exam to get the grade I want, how many marks is this roughly? My teacher seemed to think this final exam was worth 150 UMS so I would only need around 30%, but I'm not so sure? Thanks

Can anyone summarise rutherford's alpha particle scattering experiment

I think the gist of it is this:

Rutherford got a very thin sheet of gold foil and surrounded it with detectors, it was thought that nuclei were amorphous blobs with electrons lying inside (like blueberries inside a blueberry pie)

He fired alpha particles (helium nuclei) at the gold foil, seeing how many would be scattered over 90 degrees and get sent backwards; he thought that most bounce off the blob shaped atom

Most nuclei traveled through the gold foil though and reached the detectors without scattering, showing that an atom is actually mostly empty space

Some particles did scatter though, because a few of them were fired in the direction of one of the tiny nuclei - and because F=kQq/r^2 and both the alpha particles and the gold nucleus is positive as it approaches the gold nucleus the repulsive force would increase (as r (or distance) decreases and F is inversely proportional to r^2) causing them to bounce back or change their direction

This showed him that nuclei were positively charged, tiny (as most of an atom is empty space), very dense and that electrons must travel around the nucleus a large distance away to give the atom its circumference


Not sure if that's a good explanation or not - still learning it myself but I think that's the general idea. There's also a way to work out how close an alpha particle would get to a gold nucleus before being rebounded (Initial K.E = electric potential energy = kQq/r) which the CGP book explains well.

EDIT: just seen you delete it so this might have been for naught - good revision for me though

Anyone know of where to find the January 2010 past paper?

Thanks for the Ysgol link, that's helpful, couldn't find the Jan 2011 anywhere before there! REALLY want to find as many past papers as possible for this, as i learn best just through doing the past papers and learning from my mistakes!

Are the Legacy papers quite a similar structure/questions (for sections A+B) to the new spec? Would they be worthwhile running through as practice papers for this new spec?

Christ, I've only just realised this is on the 21st. I thought G494 and this were the other way round, seeing as that would be logical. My fault for forgetting this is OCR, and Advancing Physics at that.

A very ridiculous course! Do you need any help with any topics?

The whole thing would be nice I'm way behind where I should be on revision, I've been concentrating on my next two exams with are maths (16th and 20th), and was planning on cramming over the coming weekend for G494. Would of then had a week to concentrate solely on G495. This was before I realised G494 and G495 were the wrong way round.

Haven't even taken a peek at the pre-release yet. Although this is my third year of taking the course, completing two years as normal, and then retaking all the exams throughout this year, so I've become pretty used to the exam layout.

Will be back once I've done a bit of a recap on the whole exam, I'm sure I could use your help on some topics

This is my third year doing this course as well. But man, even with in-depth knowledge, I still get burned by some of the question they ask. They just pull the most random things out of their you-know-where. If this was AQA A, I would have found physics A LOT easier.

Just mention the topics and I will try my best to explain them

I'm guessing you sat the London Underground exam then? OCR excelled themselves with that paper.

That's not even their worst paper. I have sat about three/ four OCR B papers that were worse! OCR B really shouldn't be an exam board.

Haha that's so true, it really shouldn't! This year's G492 was the worst i think

if anyone is feeling confident about the advance notice, I found this perfect set of questions and although I have answered most, i'm wondering if anyone is brave enough to try and complete it and post it up with answers on here for discussion aha..

http://www.school-portal.co.uk/GroupDownloadFile.asp?GroupId=642525&ResourceID=3903515