AQA PHYA4 ~ 13th June 2013 ~ A2 Physics

Can anyone else confirm that the y axis was change in flux linkage?

and i'm going to school tomorrow, i'll ask my teacher if they have a copy of the paper :P

that diagram is showing a positive cosine graph for flux

and apparently the flux graph in that exam was negative

Huh... you're not making sense.

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IT definitely did not say change in flux linkage, if it did the gradient of the line would not represent the emf, but the change in change of flux linkage. No one plots a graph of change in flux linkage against time lol

EDIT: actually that is the same as emf against time but that's the graph they asked you to draw so they definitely wouldn't print it in the paper in the first place

Lmao I actually thoughht that when i turned the page it would be a 6 marker All in all not bad paper could have been harder. wbu?

Hi guys, just had one question about the exam which has been puzzling me. I may have incorrectly read the question, but correct me if I'm wrong:
In the question regarding the parallel discs where it asked the time between consecutive sparks if the capacitance were to be increased. I understand the logic behind thinking that if capacitance goes up, then the time constant goes up, therefore the time between sparks increases. However i specifically remember the question telling us that the current (rate of flow of charge) was constant, hence the system would not be an exponential increase of charge but rather a constant increase in charge. Therefore for a greater capacitance, a smaller charge must be stored to achieve the required 30'000V, therefore the time between sparks would in fact be shorter. Please explain to me if my reasoning is correct?
I specifically remember asking myself whether this was a trick question and gave it an extra thought.

in the exam, there were two graphs

one was showing how flux changes over time, and this graph was minus cosine (unless someone remembers it was something else?)

and the second graph below was the one which we had to use to draw how emf varies

the CGP flux graph posted robmarkey shows a positive cosine graph, and it shows a positive sine graph for emf

so what I was saying is that the graphs in the CGP book is not exactly the same as in our exam

from what i can remember the y-axis was change in flux linkage
emf is the rate of change of flux linkage
so the gradient gave the emf
i dont know i might be wrong but thats what i can remember we'll see when someone gets hold of the paper

Yh so the answer to ours is -sin. I thought you were saying it isn't

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Guys and girls...since we're still debating the +/- sine curve....can we also debate that multiple choice ratio question where most people got 2/3 but people are saying the answer is 1/3? Is it concrete that the answer is 1/3?

I'm just clutching on to straws here really.. Should have f'ing started revising earlier.

im hopingg.. the grade boundaries are similar to the took in jan... man.. physics is just too hard

The graph was negative....yea I did say change In flux I've got the paper here.

The graph was negative....yea I did say change In flux I've got the paper here.

If you've got the paper then upload it. Not like anyone's been asking for it you know..

I'm filling in the answers but I got to check them so there not uploaded with silly mistakes, it will be up first thing tomorrow section B anyway.but I can assure you that the graph is negative!

I'm filling in the answers but I got to check them so there not uploaded with silly mistakes, it will be up first thing tomorrow section B anyway.but I can assure you that the graph is negative!