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

ImageUploadedByStudent Room1433929268.309984.jpg

This is what I think the 6 makers is going to be. I'd appreciate it if someone could probably add to it

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Reply 3261

JaySP

3

Original post by gcsestuff

This is what I think the 6 makers is going to be. I'd appreciate it if someone could probably add to it

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Very similiar to mechanics ISA so I have my doubts whether the 6 marker would be bridge with resonance.

Reply 3262

JJBinn

2

Yeah the EMPA was on SHM as well, I reckon the 6 marker will be transformer/EM induction based

Reply 3263

CD223

OP

10

Any ideas of an EMI related six marker?

Reply 3264

gcsestuff

2

Just done the 2014 6 marker on an old syllabus paper. That means Thursday's 6 marker could be out there 😳😳😳😳

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Reply 3265

CD223

OP

10

Original post by gcsestuff

Just done the 2014 6 marker on an old syllabus paper. That means Thursday's 6 marker could be out there 😳😳😳😳

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Could you post which syllabus papers you're doing?

Reply 3266

JJBinn

2

Original post by CD223

Any ideas of an EMI related six marker?

Maybe the classic what happens if this magnet gets dropped through this solenoid. They will probably be able to beef that into a six marker with reference to lenz's law, faraday's law and changes to the acceleration of the magnet

Reply 3267

gcsestuff

2

Just the ones from tomreds blog. On his unit 4 section, I think it was jan 09 I just did and it was there

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Reply 3268

Absent Agent

21

guys,
i haven't had the chance to upload the feedback files on here as i usually don't have access to a PC but now I'm using the public library and i was wondering if anyone of you has a google drive or something so that i could give the files to them and they could give us a link to them as they are more than 1 Mb and i cannot compress them to less than that.
thanks

(edited 8 years ago)

Reply 3269

gcsestuff

2

This could be a cheeky 6 marker never asked this in the new papers ImageUploadedByStudent Room1433931023.713090.jpg

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Reply 3270

Kennethm

2

Original post by gcsestuff

This is what I think the 6 makers is going to be. I'd appreciate it if someone could probably add to it

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I dont think saying that dampening changes the natural frequency is correct? Someone tell me if Im wrong. The rest looks pretty good here is what I wrote:

if a question went something like - 'bridges blah blah resonance blah blah dampening blah blah, answer must include blah blah'

bridges must be fitted with dampening systems because bridges are exposed to many external forces acting upon it at any given time. Without dampening these forces may set the bridge in violent (or damaging) motion when the natural frequency of the bridge matches the frequency of the periodic force applied to the bridge - for example people walking on the bridge with a matched frequency (soldiers marching.)

Pretty sure people could add to this. Hope it helps too.

Reply 3271

Kennethm

2

Original post by JJBinn

Maybe the classic what happens if this magnet gets dropped through this solenoid. They will probably be able to beef that into a six marker with reference to lenz's law, faraday's law and changes to the acceleration of the magnet

Thats already been done. I know they've done transformers for 6 markers like 3 times now but there is a lot of content on transformers where as there isnt much to say about EMI. There might be a question on a rotating coil and how/when/where the magnetic flux is a maximum compared to when the emf is a maximum. That could confuse a lot of students as some people don't explicitly know the difference.

Reply 3272

palaseum9

2

Original post by JJBinn

Maybe the classic what happens if this magnet gets dropped through this solenoid. They will probably be able to beef that into a six marker with reference to lenz's law, faraday's law and changes to the acceleration of the magnet

That's an absolute beauty of a six marker <3

Reply 3273

AR_95

21

Would love the Bridge SHM one

Reply 3274

Sbarron

3

If an alternating current just keeps goes backwards and forwards then wouldn't the force just keep going backwards and forwards perpendicular to it?

I can sort of see that the field would still go in the same direction using LHR but how does it induce an alternating voltage if it's not changing direction?
how does the voltage size change from one side of the transformer to the other using transformer and where does the difference go??

Is the alternating current actually alternating or do they mean going left on one side of the coil and right in the other?? Then surely it's not alternating it's just a continuous flow in the same direction

(edited 8 years ago)

Reply 3275

EEngel95

Do we have to use our rounded values from the previous part of a question, or can we use the exact value.

Reply 3276

Sbarron

3

Original post by Kennethm

Thats already been done. I know they've done transformers for 6 markers like 3 times now but there is a lot of content on transformers where as there isnt much to say about EMI. There might be a question on a rotating coil and how/when/where the magnetic flux is a maximum compared to when the emf is a maximum. That could confuse a lot of students as some people don't explicitly know the difference.

And could you explain the answer to that please??

Reply 3277

IWantSomeMushu

17

Wtf? I think it could be down to the wording of the question...

Original post by NEWT0N

emf induced is at a pi/2 phase difference between flux linkage. When magnitude of flux linkage is maximum emf induced is 0, and vice versa. The emf induced is maximum when the coil is parallel to the field lines because the coil cuts the flux lines perpendicularly at that instant. Flux linkage is easier to guess intuitively as it becomes maximal when the coil is perpendicular to the field.