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AQA Physics Unit 4 Thread - JAN 28th 2010 (Post Exam) watch

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    Unless there is already a thread for this and I have failed to find it what are your thoughts for those of you taking the exam?

    I have found the magnetic stuff quite hard?

    Cheers
    Henry
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    The magnetic stuff is quite hard, expecially the flux linkage and emf induced stuff. Im finding the Dynamo/Motor Rule questions quite easy though.

    I'm also struggling with Gravitational/Electrical Potential. omg, so much to revise >__>
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    Is this Physics A?
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    personally im found gravitational fields the hardest, but electric fields helped me to understand it more so it has clicked now
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    Yeah I'm doing this. First time doing multiple choice questions since GCSE - should be interesting!!

    Why does the title have "post exam" in brackets? Am I missing something ... ?
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    Could someone tell me what percentage of the paper is composed of multiple choice? Also, do we have both parts/sections of the paper to complete at the same time? If so then we can use both parts together which will help as some questions will have a slight overlap.
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    there are 50 marks for the written bit and 25 for the multiple choice bit, i think anyway. yeah that could help but if we did have both parts a the same time the exam board would be wise to it.
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    (Original post by NAJC)
    Could someone tell me what percentage of the paper is composed of multiple choice? Also, do we have both parts/sections of the paper to complete at the same time? If so then we can use both parts together which will help as some questions will have a slight overlap.
    25 marks multiple choice, 50 written. 1 hr 45 mins to do both sections.
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    Okay I assume you guys are doing Physics A. I'm doing Physics B. You guys get multiple choice questions? Whaaaaat!?
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    i think im going to fail thsi exam
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    I need serious help on this paper ! I don't quite understanding anything. Does anyone have any revision guides on the topics of unit 4?
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    Theres a CGP one, and yeah, I got a bad feeling about this one.
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    well if anyone has any questions, ask away!
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    (Original post by Robofish)
    well if anyone has any questions, ask away!
    Is damping always in the opposite direction to velocity or displacement? How do you know when to use which Fleming hand rule?
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    (Original post by NAJC)
    Is damping always in the opposite direction to velocity or displacement? How do you know when to use which Fleming hand rule?
    Flemings left hand rule is for converting electricity into motion. The right hand rule is for converting motion into electricity.
    I'm fairly sure damping is always in the opposite direction to the velocity, as it is trying to reduce the velocity each cycle.
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    (Original post by Danny A G)
    Flemings left hand rule is for converting electricity into motion. The right hand rule is for converting motion into electricity.
    I'm fairly sure damping is always in the opposite direction to the velocity, as it is trying to reduce the velocity each cycle.
    Oh, so when you are moving a magnet through an electric field, or a coil through a magnetic field, you use the right hand rule? And for the left hand rule you use it when?

    But doesn't damping also oppose the amplitude of the oscillation, as this decreases with every cycle?

    Thanks for the reply, +rep.
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    (Original post by NAJC)
    Oh, so when you are moving a magnet through an electric field, or a coil through a magnetic field, you use the right hand rule? And for the left hand rule you use it when?

    But doesn't damping also oppose the amplitude of the oscillation, as this decreases with every cycle?

    Thanks for the reply, +rep.
    The left hand rule = motor effect
    Right hand = generator

    And yes the amplitude will be increasing if the velocity is in that direction. The velocity and amplitude are in the same direction
    The damping is like a friction which reduces the amplitude in each cycle.
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    (Original post by NAJC)
    Is damping always in the opposite direction to velocity or displacement? How do you know when to use which Fleming hand rule?
    Velocity, so which every way it moves, it has a force acting against it. The bit I don't like is the resonance area, especially explaining it.
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    from my textbook i know that the negative of the potential gradient is the electric field strength...what can this tell you about a field, i.e what does a positive electric field strength tell you about the direction of the field etc (same for negative) im confused on this
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    http://store.aqa.org.uk/qual/gce/pdf...GPHYA4ASQP.PDF
    hi i need help on the above link

    Q 14 - where does the 2 come from? should it not be 2 on the top??

    Q- 16 can someone help please

    Q - 17 - I understand it accelerates as it changes direction but does it not also go in a circular motion?

    THe answers are at the bottom

    Also if you have not seen this paper before I hope it helps! and i hope you help me lol
 
 
 
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