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

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Reply 160

Revolution is my Name

Particles: :borat:

Radiation: :borat:

Electric fields: :borat:

Magnetism: :bawling:

Reply 161

Summerdays

Original post by Revolution is my Name

Particles: :borat:

Radiation: :borat:

Electric fields: :borat:

Magnetism: :bawling:

What are you stuck on so that I can ATTEMPT to explain it?

Reply 162

Summerdays

Original post by Mikkels88

71.... cus im a boss

You get an extra mark because you're Chuck Norris :biggrin:

Reply 163

Mikkels88

chuck norris wouldnt even sit the paper, the paper would do chuck norris studies... and fail

Reply 164

jimmeh

Original post by Revolution is my Name

Particles: :borat:

Radiation: :borat:

Electric fields: :borat:

Magnetism: :bawling:

I could not agree more...It doesn't make any sense. I can just about cope with calculations, but as soon as I see "explain" in a magnetism question, I might as well write a note to the examiner asking for a mark or two out of sympathy...

Reply 165

Summerdays

Original post by Mikkels88

chuck norris wouldnt even sit the paper, the paper would do chuck norris studies... and fail

OCR... recognising pwnership :cool:

Reply 166

41jms

Original post by Revolution is my Name

Particles: :borat:

Radiation: :borat:

Electric fields: :borat:

Magnetism: :bawling:

same here!!

iv come to accept that my brain and magnetism just dont work!! i think il just have to learn a few things off byheart and hope for the best.. i used to love physics last year! managed an A cause the topics were interesting, this particular exam however :/ i just do not understand magnetism and im not a fan of electric things either! grrrrr.

Reply 167

a93

can someone please explain the correct meaning of the meridian, i dont know if its an imagenary line covering the whole earth, from north to south, or from north to the equator.

Also im having some difficulty with the michelson interferometer; i just dont get how to measure the wavelength from it, how the dark and bright fringes correspond to the wavelength and so on. Ive forgot all the AS stuff, if anyone can explain it to me it would be much appreciated.

Reply 168

41jms

Original post by jimmeh

hahaha, after a long hard day of trying to understand magnetism (and failing) you managed to make me smile with this :tongue:

looks like magnetism isnt a favourite then! lets hope most people mess up on this and grade boundaries are low.. (doubtful unfortunately :frown:

)

Reply 169

Rogercbinboy

Original post by a93

Meridian is an imaginary line going from the north pole to the south pole in a semicircle (if the earth was a perfect sphere it would be anyway), and when it says "one minute of an arc" or whatever it was a minute is a 60th of a degree.

As for the michelson interferometer I'm not that **** hot but the idea is that if one mirror is moved one quarter of a wavelength in either direction then the light will be half a wavelength out of phase from the other light reflecting off the other mirror (as it travels there and back so the quarter doubles); if the light is half a wavelength out of phase then there's destructive interference and they basically cancel each other out giving the dark fringe, whereas if they're in phase then there's constructive interference so there's a bright fringe. Then if you moved it another quarter of a wavelength in the same direction they'd be in phase again.

Reply 170

Summerdays

Don't forget that the distance from the poles to the equator is a quarter of the circumference of the earth...

Reply 171

Rogercbinboy

Can someone confirm this order with transformers:

The alternating current in the primary coil induces a flux in the iron core, this travels through the secondary core and induces an alternating voltage in the secondary coil.

Then with the eddy currents:

The alternating current in the primary coil induces a flux in the iron core, this creates an emf in the core since it's a good conductor of electricity and that causes currents in the core that create their own flux, and because of Lenz' law these flux lines oppose the original flux decreasing the overall flux.

That sound right/in the right order?

Reply 172

Summerdays

Original post by Rogercbinboy

Can someone confirm this order with transformers:

The alternating current in the primary coil induces a changing flux (linkage) in the iron core, this travels through the secondary core and induces an alternating voltage in the secondary coil.

Then with the eddy currents:

The alternating current in the primary coil induces a changing flux (linkage) in the iron core, this creates an emf in the core since it's a good conductor of electricity and that causes currents in the core that create their own flux, and because of Lenz' law these flux lines oppose the original flux decreasing the overall flux.

That sound right/in the right order?

Yes, that's perfect. I bolded in one extra bit.

EDIT: The primary coil doesn't induce flux in the core. The flux travels through the core.

(edited 12 years ago)

Reply 173

Helsy

Original post by Summerdays

It's not something you really need to know :smile:

EDIT: But it is an emf that is induced that works against the original emf.

Ok, thanks. :smile:

But if it turns up now I shall KILLLLLLLLL you! :wink:

Original post by Summerdays

60 - 63. I always lose around 7 marks at least.

Holely molely, I am screwed on Tuesday. :frown:

Reply 174

Rogercbinboy

Original post by Summerdays

Yes, that's perfect. I bolded in one extra bit.

EDIT: The primary coil doesn't induce flux in the core. The flux travels through the core.

Decent, cheers.

Just need to power through section C tomorrow then I should be alright, which is a surprise since I've never felt prepared before a physics exam before.

Reply 175

Summerdays

Original post by Rogercbinboy

Decent, cheers.

Just need to power through section C tomorrow then I should be alright, which is a surprise since I've never felt prepared before a physics exam before.

I have never been more prepared for a physics exam in my life (same wit hthe G494 resit.)

Who's done the june 2010 paper? I hope the paper we get is as difficult as that one.