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

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look at this guys: http://www.johnbright.conwy.sch.uk/depts/science/Content/Past_Papers/Y13/Physics/2003JuneMSA2.pdf

as it doesnt have page number type in the find (Ctrl + F) "cosine curve" it'll take you to the bit im on about.. erm the faint line on the graph is flux linkage. it asks you to draw on the graph how the voltage across the coil changes with time.

Can someone please explain how that markscheme is right?

I thought voltage was proportional to negative gradient. therefore the graph would look a bit different, like stationary points would still be the same but the maxima and minima the other way round?

Yes, they drew it (technically) the wrong way round. But you would still gain the marks :smile:

Reply 101

41jms

Original post by Summerdays

Yes, they drew it (technically) the wrong way round. But you would still gain the marks :smile:

thanks! could you possible explain 10 c on the same paper for me?

heres the question, page 11: http://www.johnbright.conwy.sch.uk/depts/science/Content/Past_Papers/Y13/Physics/2864June2003.pdf

thanks so much!!

Reply 102

Summerdays

Original post by 41jms

The fraction will decrease because the protons now have a greater speed (due to having a greater kinetic energy), which means that the time the lead nucleus has in trying to repel the protons (with a force 1.6x10^-19N) is less. Thus, the impulse acting on each proton is less and thus, less protons are scattered by 90 degrees.

Reply 103

41jms

Original post by Summerdays

ahh thanks! please stay on this thread for the next few days :tongue:

Reply 104

41jms

Original post by Summerdays

tried to rep you, but i have ran out..

Reply 105

Sereni

Guys I've done most of the past papers I have and Ive gone through both the specification and the advancing physics textbook and tbh Im not really sure what else I should to to prepare... Can I have some interesting ideas rather than just go through the specification again because one of the problems is that i find it all really boring and so find it hard to actually work, and I have today and tommorow scheduled to prepare for the exam plus monday afternoon and evening. any websites that I could work through that are interesting... I just feel like if i just go through the textbook more It will be so boring I barely pay attention to the notes I make

Reply 106

Summerdays

Original post by Sereni

http://ocw.mit.edu/courses/physics/8-02-electricity-and-magnetism-spring-2002/video-lectures/

http://freevideolectures.com/Course/2876/Fundamentals-of-Physics-III

http://www.khanacademy.org/#physics

http://www.freelance-teacher.com/videos.htm

Reply 107

Sereni

Original post by Summerdays

Cheers, now im just going through them just trying to figure out which ones are on this exam :smile:

.

Also is it just me or is anyone else suspisious over how easy the advance notice material is...

Reply 108

Ollie901

Original post by Sereni

Cheers, now im just going through them just trying to figure out which ones are on this exam :smile:

.

Also is it just me or is anyone else suspisious over how easy the advance notice material is...

Yeah I am, but maybe it just will be easy?

My Chemistry exam had a 'synoptic element' and the exam was basically all AS stuff so was really quite easy, easier then the past papers at least. I'm hoping for the same with physics haha.

I still hate magnets.
Is this a morning exam?

Reply 109

Sereni

Original post by Ollie901

its morning for me (england). mm I need an A in physics to meet my med offer

Reply 110

Ollie901

Original post by firstevermember

Question 4)B)ii) 4marks for drawing this graph... I dont get why it should be a 'square pulse’ shaped graph. The mark squeme is at bottom of pdf.

http://www.ocr.org.uk/download/assess_mat/ocr_7977_sam_gce_unit_g485.pdf

(Got 68/100 on this paper, question 7 i got 1/10 :biggrin:

)

Jesus Christ. Was panicing like hell looking through that paper then, then I realised its OCR A.

Reply 111

Zagreus_92

Original post by Ollie901

Jesus Christ. Was panicing like hell looking through that paper then, then I realised its OCR A.

Yer me too, I read cosmic background radiation and I was like "When did we ever learn that :confused:

" But yes, then realized it was OCR A

Reply 112

firstevermember

LOOOOOL sry about that... ive done that before when looking at a Physics B.

Reply 113

41jms

Can someone please explain magnets/motors to me please pleasee?! :frown:

Reply 114

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.

Reply 115

Fifi93

Does anyone have any resources for revision notes??? I find the textbook is really unhelpful and the CGP book doesn't go into much depth. :s-smilie:

Thanks for all the questions on the pre-release they've been really helpful. :smile:

Reply 116

bear54

can someone explain question 3bii) from the Jan 06 paper to me? It's a one mark question and the answer is 1.8ev, i have no idea how they got that

Reply 117

JoeCarr

After comparing my answers with Summerdays, here are the ones where I differed, or used a different method, all the others I got the same answer. The vast majority seem right to me :smile:

Spoiler

ALL OBSOLETE NOW WITH ANSWERS GIVEN ON PAGE 7!!!

I'll add more tomorrow hopefully. :biggrin:

(edited 12 years ago)

Reply 118

Summerdays

Original post by JoeCarr

After comparing my answers with Summerdays, here are the ones where I differed, or used a different method, all the others I got the same answer. The vast majority seem right to me :smile:

Spoiler

I'll add more tomorrow hopefully. :biggrin:

Thank you very much :biggrin:

I will have a look at your solution, and the ones you think I got right, to revise this section C :tongue:

Reply 119

Summerdays

Original post by bear54

can someone explain question 3bii) from the Jan 06 paper to me? It's a one mark question and the answer is 1.8ev, i have no idea how they got that

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.