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OCR Physics A G485 - Frontiers of Physics - 18th June 2015

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Original post by sagar448
Yeah I know :C. I'm very scared I just hope I don't mess up.

EDIT: There still maybe a chance to find out if they are going to be hard or not. I'm retaking the G482 which is on the Thursday of this week, and if that one goes well, I'm guessing the others will be fine too. :biggrin:


Please let me know how that goes!!!
Original post by chem@uni
Please let me know how that goes!!!


Okz. :3
For question 3.c.ii. for june 2013

http://www.ocr.org.uk/Images/175460-question-paper-unit-g485-01-fields-particles-and-frontiers-of-physics.pdf

heres the link if you want to look at it

theres a electric field down and a magnetic field up, with an electron passing through it.
The magnetic field force is increased. The mark scheme says 'the electron drift 'downwards''. Why is this?

I thought they would drift up
(edited 8 years ago)
Original post by Username13
For question 3.c.ii. for june 2013

http://www.ocr.org.uk/Images/175460-question-paper-unit-g485-01-fields-particles-and-frontiers-of-physics.pdf

heres the link if you want to look at it

theres a electric field down and a magnetic field up, with an electron passing through it.
The magnetic field force is increased. The mark scheme says 'the electron drift 'downwards''. Why is this?

I thought they would drift up


The electric field attracts the electrons upwards since it's flowing from positive to negative but since the magnetic field is bigger the electron goes downwards.
Remember that flemings left hand rule applies for positive ions or particles, electron is negative so either use your right hand or use your left hand but the force will be opposite.
What grades have people been getting in past papers?
(edited 8 years ago)
Original post by chem@uni
What grades do people think they will get on this exam?


No one is going to answer that properly

If they say A* they'll get slated, or anything above an A

So most will say B or lower and then you'll get people saying Ds or less out of lack of confidence
Original post by sagar448
The electric field attracts the electrons upwards since it's flowing from positive to negative but since the magnetic field is bigger the electron goes downwards.
Remember that flemings left hand rule applies for positive ions or particles, electron is negative so either use your right hand or use your left hand but the force will be opposite.


aah okay

Thanks
Original post by L'Evil Fish
No one is going to answer that properly

If they say A* they'll get slated, or anything above an A

So most will say B or lower and then you'll get people saying Ds or less out of lack of confidence


Edited
Reply 488
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Original post by sagar448
The electric field attracts the electrons upwards since it's flowing from positive to negative but since the magnetic field is bigger the electron goes downwards.
Remember that flemings left hand rule applies for positive ions or particles, electron is negative so either use your right hand or use your left hand but the force will be opposite.


This is why I've been getting some questions wrong because I thought Fleming's left hand rule worked for electrons. My teacher taught us **** all so I had to learn the course myself and figure out all these small details. I read somewhere fleming's left hand rule is for conventional current.
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did anyone else try to memorise the mark scheme for the medical stuff? i memorised it and only dropped 1 mark in the june 14 paper in the medical section- it looks like the best way to revise that topic if you are comfortable with the maths in it.
Original post by ETRC
This is why I've been getting some questions wrong because I thought Fleming's left hand rule worked for electrons. My teacher taught us **** all so I had to learn the course myself and figure out all these small details. I read somewhere fleming's left hand rule is for conventional current.


Yes it is, it's only for conventional current while right hand rule for flemings is for either INDUCED current or electrons in a magnetic field. Left hand is only for like an ion in a magnetic field or conventional current.

I'm sorry to hear that about your physics teacher, it's better to learn yourself anyways since you understand more.

good luck
:biggrin:
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Original post by sagar448
Yes it is, it's only for conventional current while right hand rule for flemings is for either INDUCED current or electrons in a magnetic field. Left hand is only for like an ion in a magnetic field or conventional current.

I'm sorry to hear that about your physics teacher, it's better to learn yourself anyways since you understand more.

good luck
:biggrin:


haha thanks
i don't mind mind the paper in general but the graphs you had to draw in june 2014 were messed up especially the one where you had two positive charges and had to draw the e field graph.
Original post by ETRC
haha thanks
i don't mind mind the paper in general but the graphs you had to draw in june 2014 were messed up especially the one where you had two positive charges and had to draw the e field graph.


Oh I see, yes, it is easier if you visualise it. If you want I can help you with that question?
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Does anyone know what the requirements for an A* are. My teacher has said that it is 90% UMS in either exam, however, most other OCR exams involve a 90% UMS average over both A2 exams. I have tried to research it and nothing has came up and the OCR grade boundaries do not even show an A* on there?
Original post by sagar448
Oh I see, yes, it is easier if you visualise it. If you want I can help you with that question?


Do you mind helping me out with the resultant electric field one? The e.m.f. was a lot easier for me to do.
Original post by randlemcmurphy
Do you mind helping me out with the resultant electric field one? The e.m.f. was a lot easier for me to do.


Sure, but could you please direct me to the question or post it here? I don't remember it very well. XD
Original post by chem@uni
What grades have people been getting in past papers?


Only done 2, A*s in both

Even with this post I think I'll get slated lol
Original post by sagar448
Sure, but could you please direct me to the question or post it here? I don't remember it very well. XD


G485, June 2014, Question 1b ii
Original post by randlemcmurphy
G485, June 2014, Question 1b ii


OH yes, sure hold on I'll upload a picture with explanation.
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Original post by sagar448
Yes it is, it's only for conventional current while right hand rule for flemings is for either INDUCED current or electrons in a magnetic field. Left hand is only for like an ion in a magnetic field or conventional current.

I'm sorry to hear that about your physics teacher, it's better to learn yourself anyways since you understand more.

good luck
:biggrin:


Or, if it's an electron you can still use Fleming's left hand rule, just put you finger representing the conventional current in the opposite direction of travel of the electron.
(edited 8 years ago)

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