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

In (i) there's a sudden change in flux through Q so a current flows in Q. After that, the flux through Q is no longer changing to there is no current in Q. Result is that the ammeter deflects and then returns back to reading zero.

(ii) There's a sudden decrease in current through P, so a sudden decrease in flux through Q so a current is induced in Q in the opposite direction to when the switch was closed (before, there was an increase in flux). Then afterwards the flux through Q is constant so no current in Q. Result is that the ammeter deflects in the opposite direction to before and then returns to zero.

There was nothing to suggest that the current in Q in (ii) should be less than that in part (i).

Unofficial Mark Scheme

Start posting everything you can remember about the questions/answers here and I'll update the first post as we go along.

Hello guys, I know the unit for Flux Linkage is Wb Turns, but I missed of the turns and wondering if they have any lenience to this, for some reason I think it's come up before.

Shall I do this in the first post? It would be best for everyone to PM me as much as they can remember!


Posted from TSR Mobile

look, hard paper or not, its all relative. Wev all found those wordy questions difficult and it was easy to lose marks on the rest of Section B today. that being said it wasn't a particularly challenging section A althought 4 or 5 where kinda discriminating. what im saying is they could have given us the easiest paper ever, but if WE AS A NATION did awful then the boundaries would be low. Today, if people are saying its easy then the boundaries may not fully reflect this as its all about how we actually did

Good idea to put the answers there when agreed upon but I think it's good to have a dedicated place to discuss/argue about questions without general chatter

wouldnt the resistor affect it tho ?

Sure. Can someone find Merhdad's answers to the MC? So we can debate them?


Posted from TSR Mobile

hey dude, how did you feel about the paper?

Yes but it's the rate of change of flux that counts. If the current through P changed more quickly when the resistance was changed than when S was closed (unlikely but not impossible, the converse wasn't implied), then the current in Q in (ii) would be greater than in (i).

Not too bad to be honest. It was a fair paper, I just made a few silly errors. Only thing that angers me is the typo.


Posted from TSR Mobile

Sure. Can someone find Merhdad's answers to the MC? So we can debate them?


Posted from TSR Mobile

Is that the exact username? I can't find the account to search the post history..

As I wrote lots of different marks to get the marks in some questions, some of my answers were not written on the dotted lines coz i didnt have enough space.
Will the answers which are not on the dotted line be still marked ?

As I wrote lots of different marks to get the marks in some questions, some of my answers were not written on the dotted lines coz i didnt have enough space.
Will the answers which are not on the dotted line be still marked ?

That probably depends on the examiner. I'm sure if they're easy to spot as an answer they'll get marked