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AQA Physics PHYA4 - 20th June 2016 [Exam Discussion Thread]

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The mean percentage mark on Section A by year:
Jun15-66.8%
Jun14-66.8%
Jun13-60.4%
Jan13-66.0%
Jun12-63.2%
Jan12-68.0%
Jun11-58.0%
Jan11-63.0%
Jun10-59.0%
Jan10-64.0%

Just goes to show how important past papers are maybe, as there is no way Jun10 was harder than Jun15 :biggrin:

Are there any mark schemes to those papers?
Original post by MintyMilk
My thought process went like this:

>imagine P and one of the charges as its own system to simplify things initially
>consider the potential at P in this simplified system and what that value would physically represent: a charge differential that causes a force
>now imagine what would happen if another one of those charges were added to the system
>it would double the quantity of stuff acting on P

I didn't do any calculations, but it was clear based on the numbers that 180 was there to represent one charge's potential, and 360 to represent 2 charge's worth of potential, so I guessed 360

As far as what you're saying about forces cancelling goes, I think that would represent the physical, resultant movement of P rather than having an effect on the raw potential the individual charges produce, maybe.


does it mean because this is asking for the electric potential, you just add the total of the Vs?
and if it's asking you for the electric field, it will cancel out?
also if you're asked to find the electric field, do you have to take components?
very confused :s-smilie:
Hi Again,


I did post before about emailing out question packs



I just have my D1 exam this afternoon so will be emailing as soon as I finish that.


Sorry for the wait, and thanks to everyone who has taken an interest in this !


Cheers,

Will
For anyone wanting the Unit 4 papers


Please inbox me your email or email : [email protected] and I can email you back the papers


I am sending out the papers now to the people who have in-boxed me already requesting such.


Enjoy!!

Will
Original post by blueberry389
does it mean because this is asking for the electric potential, you just add the total of the Vs?
and if it's asking you for the electric field, it will cancel out?
also if you're asked to find the electric field, do you have to take components?
very confused :s-smilie:


I found a similar question in an earlier paper that effectively showed two positive charges equidistant from one another creating a resultant positive in the middle. From this I think we can assume that this is how we should go about considering potential in general, i.e. positive charges simply don't cancel.

In the context of the triangle question, I guess this means that both the horizontal and vertical components of each force contribute to the total potential (whatever that physically represents) at the point P, so it must not be necessary to take components

https://youtu.be/GfiYLCoxicE?t=13m8s
(edited 7 years ago)
anyone think a certain 6 marker is more likely?
Reply 409
Original post by thestarter
anyone think a certain 6 marker is more likely?


I reckon it will be on emf/magnetic fields
I resat both unit 1 and unit 2 which were pretty difficult exams this time round so i reckon they will choose a harder topic such as that

Therefore I reckon a six marker on capacitors is out of the question no matter how much how I would love it to be on that :hmpf:
Probably something on transformers or magnetic fields, they've said in a number of examiners reports that students struggle on these topics, it wouldn't surprise me if they ended the last paper of the spec with a bang.

Looking forward to it :cry2:
Original post by rory58824
Probably something on transformers or magnetic fields, they've said in a number of examiners reports that students struggle on these topics, it wouldn't surprise me if they ended the last paper of the spec with a bang.

Looking forward to it :cry2:

There have already been two 6 markers on transformers IIRC - one on how to reduce power loss and the other on how they're used to transmit power across the national grid.

I reckon it will be on a practical to do with capacitors
Original post by TajwarC
There have already been two 6 markers on transformers IIRC - one on how to reduce power loss and the other on how they're used to transmit power across the national grid.

I reckon it will be on a practical to do with capacitors


That would be lovely!!!
Original post by rory58824
That would be lovely!!!


Indeed, similar to the 6 markers from unit 1
Hi all,



I have been messaging people via email and stuff with papers I have created myself


here is a unit 4 section B style paper and I have created a MS to go with it.

Enjoy !!

Will
In which case do we need to use flemings right hand rule? Is it when it's the motor effect?
http://filestore.aqa.org.uk/subjects/AQA-PHYA4-2-W-QP-JUN10.PDF

4a i really hate magnetic fields i honestly dont get how its -z i keep getting +z with force inwards and second finger the direction of electron
Original post by liverpool2044
http://filestore.aqa.org.uk/subjects/AQA-PHYA4-2-W-QP-JUN10.PDF

4a i really hate magnetic fields i honestly dont get how its -z i keep getting +z with force inwards and second finger the direction of electron


Force is to the middle as it's a centripetal force because it's moving in a circle, the electron has a negative charge so you have to treat it as a positive charge going anti-clockwise. :smile:

Edit: I should have said positive charge in the +y direction to make it clearer, but that's the overall idea :smile:.
(edited 7 years ago)
Original post by particlestudent
Force is to the middle as it's a centripetal force because it's moving in a circle, the electron has a negative charge so you have to treat it as a positive charge going anti-clockwise. :smile:

Edit: I should have said positive charge in the +y direction to make it clearer, but that's the overall idea :smile:.


ah okay so negatives travel in opposite direction to the positive? is this similar in electric fields?

which travel with the force and opposite the field
Original post by liverpool2044
ah okay so negatives travel in opposite direction to the positive? is this similar in electric fields?

which travel with the force and opposite the field


Yes, a negative charge moving to the right for example has to be treated as a positive charge moving to the left.

Electric field lines show you the direction a positive charge would move if it was placed in that field.

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