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# OCR Physics B G495 Field and Particle Pictures June 21st 2011 Exam Thread watch

1. (Original post by wki)
does it mean that if it alternating current a.c , then the flux linkage is alternating?
what if it's dc then? Have I messed them all up?
You can only induce an emf in the second coil if the flux linkage is alternating. A d.c transformer wouldn't work as far as I'm aware, there'd be no emf induced in the second coil.
2. (Original post by Geekchic17)
Er Southampton/Sheffield
Sheffield more likely cause it's lower grades haha
What are you wanting to do? and where?
Chemistry. Imperial is my firm
3. (Original post by Summerdays)
Yes for the first part.
D.C is direct current... which isn't alternating. A commutator, if you're referring to a motor, is used though.
oh yeah I remembered something called split ring communtator, in motor? how does it work? is it everytime the loop turns to verticaL position, the current opposed / actually the loop reversed?
4. I am going to sleep guys. I HAVE HAD ENOUGH. Good luck everyone
5. (Original post by wki)
oh yeah I remembered something called split ring communtator, in motor? how does it work? is it everytime the loop turns to verticaL position, the current opposed / actually the loop reversed?
The current changes direction every half loop, causing the rotor coil to roatte at a steady speed
6. (Original post by Summerdays)
I am going to sleep guys. I HAVE HAD ENOUGH. Good luck everyone
Cheers ! You hero helps me a lot
7. (Original post by wki)
oh yeah I remembered something called split ring communtator, in motor? how does it work? is it everytime the loop turns to verticaL position, the current opposed / actually the loop reversed?

(Original post by Summerdays)
The current changes direction every half loop, causing the rotor coil to roatte at a steady speed
I believe that a split ring commutator is (as the name suggests) split in half too, otherwise it'd end up losing energy each time the current is reversed, so it'd eventually just stop. Don't quote me on the exact reason though, this is digging deep into the depths of my memory!
8. (Original post by Summerdays)
I am going to sleep guys. I HAVE HAD ENOUGH. Good luck everyone
Gonna do the same - pleasure revising with you.

Cheers for the help people and good luck.
9. (Original post by Swindan)
You can only induce an emf in the second coil if the flux linkage is alternating. A d.c transformer wouldn't work as far as I'm aware, there'd be no emf induced in the second coil.
that makes sense, Thanks need some more hard work tonight'
10. good luck lads (and that one girl), post on here after how you think it went
11. Is that everyone then, or are there any nocturnal revisers such as myself?
12. is it me, or was jan 09 a really hard paper. Please someone tell me it was, just had a right confidence knocking.
13. (Original post by Ollie901)
is it me, or was jan 09 a really hard paper. Please someone tell me it was, just had a right confidence knocking.
I just got like 70% for it which Im worried and thinkin to stay up a while for that n the lovely advance notices. Good luck !!
14. Daym, this thread is monstrous. Good luck guys for tomorrow, Im quietly ****ting myself, this exam will determine whether or not I go to Uni next year. No pressure.
15. (Original post by Swindan)
Is that everyone then, or are there any nocturnal revisers such as myself?
i think im guna be up for a while. Cant get my head around this damn advance notice article
16. Really quick question if anyone's still up:

Jan 08, question 9: the answer is kinetic energy, but how do you work that out?
17. (Original post by R.Fanatic)
i think im guna be up for a while. Cant get my head around this damn advance notice article
I've read it once so far I've been concentrating on Sections A and B really, I might have a bash at the questions someone posted on this thread regarding the pre-release in the morning. Everyone's spoken about them positively, so go back a few pages and find them if you haven't done them yet.
18. (Original post by Swindan)
Is that everyone then, or are there any nocturnal revisers such as myself?

Yup hi me....

Been revising from about 4:30 pm till now....

But obviously with breaks....

Just got the quark bit and the nucleus bits + pre release....

But I'm hoping to do pre release in the morning.... By that I mean wake up super early ha....

How you doing? When did you start revising? (annoyingly I started late, as usual) ... I was like nah it's easy bla bla... Then bam.... Ohhh shooot, you've got barely any time to do all this work... So yeh, just waiting for c4
19. (Original post by Swindan)
I've read it once so far I've been concentrating on Sections A and B really, I might have a bash at the questions someone posted on this thread regarding the pre-release in the morning. Everyone's spoken about them positively, so go back a few pages and find them if you haven't done them yet.
yer i found it, thanks. I just did a past paper and got 60% am i going to fail or what
20. (Original post by Soppe)
Yup hi me....

Been revising from about 4:30 pm till now....

But obviously with breaks....

Just got the quark bit and the nucleus bits + pre release....

But I'm hoping to do pre release in the morning.... By that I mean wake up super early ha....

How you doing? When did you start revising? (annoyingly I started late, as usual) ... I was like nah it's easy bla bla... Then bam.... Ohhh shooot, you've got barely any time to do all this work... So yeh, just waiting for c4
I was stressed earlier, but I'm a bit more eased now. I only really started revising on Saturday, awful I know. Then I concentrated on C4 on Sunday, got home after C4 and had a power nap, been revising this since.

To be honest it took me a while to realise this was even G495, I just assumed when I browsed over my exam timetable this would be G494, so that came as a bit of a shock a week or two back :L

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