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

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    Particles: :borat:
    Radiation: :borat:
    Electric fields: :borat:
    Magnetism: :bawling: / / :emo:
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    (Original post by Revolution is my Name)
    Particles: :borat:
    Radiation: :borat:
    Electric fields: :borat:
    Magnetism: :bawling: / / :emo:
    What are you stuck on so that I can ATTEMPT to explain it?
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    (Original post by Mikkels88)
    71.... cus im a boss
    You get an extra mark because you're Chuck Norris
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    chuck norris wouldnt even sit the paper, the paper would do chuck norris studies... and fail
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    (Original post by Revolution is my Name)
    Particles: :borat:
    Radiation: :borat:
    Electric fields: :borat:
    Magnetism: :bawling: / / :emo:
    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...
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    (Original post by Mikkels88)
    chuck norris wouldnt even sit the paper, the paper would do chuck norris studies... and fail

    OCR... recognising pwnership :cool:
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    (Original post by Revolution is my Name)
    Particles: :borat:
    Radiation: :borat:
    Electric fields: :borat:
    Magnetism: :bawling: / / :emo:
    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.
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    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.
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    (Original post by jimmeh)
    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...
    hahaha, after a long hard day of trying to understand magnetism (and failing) you managed to make me smile with this

    looks like magnetism isnt a favourite then! lets hope most people mess up on this and grade boundaries are low.. (doubtful unfortunately )
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    (Original post by 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.
    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.
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    Don't forget that the distance from the poles to the equator is a quarter of the circumference of the earth...
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    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?
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    (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.
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    (Original post by Summerdays)
    It's not something you really need to know

    EDIT: But it is an emf that is induced that works against the original emf.
    Ok, thanks. But if it turns up now I shall KILLLLLLLLL you!

    (Original post by Summerdays)
    60 - 63. I always lose around 7 marks at least.
    Holely molely, I am screwed on Tuesday.
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    (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.
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    (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.
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    (Original post by Helsy)
    Ok, thanks. But if it turns up now I shall KILLLLLLLLL you!



    Holely molely, I am screwed on Tuesday.
    Don't worry, it's because I have done ALL of the past papers. How many have you done so far?
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    (Original post by Rogercbinboy)
    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.
    thanks man, that helped =D
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    (Original post by Summerdays)
    Don't worry, it's because I have done ALL of the past papers. How many have you done so far?
    :O how many exactly is all? iv done a few now.. but they dont have section cs!!
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    (Original post by 41jms)
    :O how many exactly is all? iv done a few now.. but they dont have section cs!!
    20, inluding specimen.
 
 
 
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