The Student Room Group
Uni students - Complete our survey >>
Uni students - Complete our survey >>
Uni students - Complete our survey >>

AQA Physics PHYA4 - Thursday 11th June 2015 [Exam Discussion Thread]

Scroll to see replies

Original post by Chazley123
or 0.06/0.5 = 0.12 v ?? as emf= BAN(linkage)/t - faradays law??


You don't get marks for quoting given formulas on the data sheet
Original post by JizzaStanger
Corrections in bold.

Larger resistance means lower current at all times!


thanks bud! I didn't get it right so i guessed what they might be from what peoples have said
Reply 4582
Avatar for Cmog
Cmog
2
http://www.sunnyskyz.com/happy-pictures/108/Sloth-carrying-her-baby

^unofficial mark scheme
Reply 4583
Avatar for Cmog
Cmog
2
Original post by Chazley123
or 0.06/0.5 = 0.12 v ?? as emf= BAN(linkage)/t - faradays law??


I did the same as you chazley
Original post by Protoxylic
I can't remember, but if that is true then the rotation of the coil would vary. Either way if it did say increased uniformly then the emf would be constant meaning there would be no need to ask for the mean emf.


It just said the coil was rotated 90 degrees.
Original post by Cmog


What a fail. You can see in the link its clearly not a mark scheme..:lolz:
Reply 4586
Avatar for Cmog
Cmog
2
Original post by SuperMushroom
What a fail. You can see in the link its clearly not a mark scheme..:lolz:


Lol bants
Original post by Chazley123
change in momentum equal to impulse (Ns)

rate of change of momentum - I/t (Ns/s) = (N) - equivalent to weight =mg


Are you agreeing with me that its D? (rate of change in momentum)
Reply 4588
Avatar for grn
grn
1
I don't think that solution from AQA on the graph question is fair at all, I just completely skipped it because I knew it must have been a misprint!

Not that it will make much of a difference though, honestly think I've only got about 30/75 on the entire paper at this point :frown:
Original post by NEWT0N
Hm true. Honestly I don't know. Can you run me through your answer again please? Thanks

How many marks do you think you lost overall?


Just the 0.12V mean emf is under debate atm. The rest of the paper went well.
Original post by StarvingAutist
It just said the coil was rotated 90 degrees.


By the way, can you recheck your maths. e=dN(phi)/dt so e dt = dN(phi)

So sum of all e, S(e), shouldn't equal Awsin(wt) dt, surely?

The sum of the emfs would just be a sum, not an integral since if you integrate emf forward in time you get et not S(e). Either that or I'm not following your maths correctly
Original post by Protoxylic
Just the 0.12V mean emf is under debate atm. The rest of the paper went well.


How did you get 0.12? Im pretty sure the answer was 0.08v ??
Original post by SuperMushroom
How did you get 0.12? Im pretty sure the answer was 0.08v ??


I did get 0.08V. I'm labeling it as the 0.12V Q lmao
Has anyone posted the questions/ distribution of marks? Trying to figure out if I still have a future without getting full UMS on unit 5 lol
Original post by Protoxylic
I did get 0.08V. I'm labeling it as the 0.12V Q lmao


Oh ok my bad haha, just happy someone else got 0.08v aswell :biggrin:
Original post by NEWT0N
Hm true. Honestly I don't know. Can you run me through your answer again please? Thanks

How many marks do you think you lost overall?


Bet you were laughing when the 6 marks was on your laws Newton?
Original post by Protoxylic
By the way, can you recheck your maths. e=dN(phi)/dt so e dt = dN(phi)

So sum of all e, S(e), shouldn't equal Awsin(wt) dt, surely?

The sum of the emfs would just be a sum, not an integral since if you integrate emf forward in time you get et not S(e). Either that or I'm not following your maths correctly


e = -N dphi(t)/dt
therefore Sa,b(e)dt = [Nphi(t)]a,b
No negative because of sin and cos blah blah blah

It should definitely be an integral; time is continuous.
For the how to find initial charge question, I thought of it this way

V = IR applies with the initial current being equal to V/R

Also the charge stored, Q = CV which rearranges to V = Q/C

Equating the two you get Q/C = IR, so Q = CIR

I know the area under the graph makes much more sense, but would I get any marks for this??
https://www.youtube.com/watch?v=_l1XCc4xlws

The Fuhrer reacts
(edited 8 years ago)
Please, someone reassure me that I'm not the only one who thinks that was awful? I'm really angry and upset :frown: It was just full of so many ****ty questions. I need some reassurance.

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you