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    well, I think you should draw the diagram for the linac generators ... which includes what you had said ... tubes are further apart, connected to the a.c ...Then explain how it works
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    (Original post by BCHL85)
    well, I think you should draw the diagram for the linac generators ... which includes what you had said ... tubes are further apart, connected to the a.c ...Then explain how it works
    yeah,that's the best way. If points are missed out, the diagram may just about get the marks instead.
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    I don't get that at all, (dont have either of your 2 sources either), if there is a current between the electrodes then that won't give rise to an electric potential difference between two tubes, so there will be no net transfer of electroc potential energy to kinetic energy of the particle ...
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    (Original post by habosh)
    yeah there is an electric field due to the high potential difference between the electrodes
    that's exactly what I said:confused:
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    if there is an alternating p.d surely there is an a.c.

    Also, can anyone tell me about the van de graaff generator. Issit like the linac?

    p.s cheers for the bubble chamer e.t.c notes singh fello, my teacher missed that section out [not enough time to teach us].
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    copying exactly from the markscheme
    series of tubes[Not plates] (1)
    ac between tubes/+- alternating in diagrams
    Ions spend equal time in each tube
    as tubes get longer/plates get further apart
    mention of vacuum
    see they want you to say that an ion spends an equal time in tubes this is one mark and the next one is to indicate that the tubes get longer
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    that's the june 2004 paper - 5 mark question inc clarity.

    this is the 1 set by my teacher - 6 marks exc clarity.
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    (Original post by mik1w)
    that's exactly what I said:confused:
    then dont start mixing thing up I suggest just memories that there is a high ac pd.ac means that it's alternating
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    (Original post by nas7232)
    that's the june 2004 paper - 5 mark question inc clarity.

    this is the 1 set by my teacher - 6 marks exc clarity.
    I dont get it ,in the book the diagram is drown with the plates having the same hight I mean tubes each with the same hight but with an increasing length,after all the vertical hight wont afftect the time the ion has to travel to get thorugh the tubes,so I dont get what do you mean if you would explain more,
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    You can use a.c supply without switching it off because when the charged particle is at the end of the 1st tube, the 1st tube is negative, the 2nd one is positive charge. So there's still p.d which accelerate particle. It continues with 2nd and the 3rd one...

    Van de Graaff generator is a bit different. As you have a very high potential charge hollow sphere (about 10000 V). It connects to many tubes by resistor chain. Each tube is seperated. The ion source is inside the sphere, then it passes through the tubes, and is accelerated when it passes through gaps.
    The common thing with linac generator is Van de Graaff is linear accelerator
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    (Original post by habosh)
    I dont get it ,in the book the diagram is drown with the plates having the same hight I mean tubes each with the same hight but with an increasing length,after all the vertical hight wont afftect the time the ion has to travel to get thorugh the tubes,so I dont get what do you mean if you would explain more,
    i didn't say anything about the height, i was just stating that the lengths of the tubes have to get longer as the particle is travelling at greater speeds so an increase in length is required to keep in step with the alternating pd.

    as
    t = d/s

    then the ions are in each tube at the same time. This question wont come up in this much detail, but imo its best to know 100% rather than 95% with phy6. Not that i know 100%, i'm just on the same level as you guys.
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    (Original post by nas7232)
    i didn't say anything about the height, i was just stating that the lengths of the tubes have to get longer as the particle is travelling at greater speeds so an increase in length is required to keep in step with the alternating pd.

    as
    t = d/s

    then the ions are in each tube at the same time. This question wont come up in this much detail, but imo its best to know 100% rather than 95% with phy6. Not that i know 100%, i'm just on the same level as you guys.
    maaaaaaaaan you scared me ...I know that and i agree with it 100% I though you meant the diameter gets larger for each cylinder
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    (Original post by BCHL85)
    You can use a.c supply without switching it off because when the charged particle is at the end of the 1st tube, the 1st tube is negative, the 2nd one is positive charge. So there's still p.d which accelerate particle. It continues with 2nd and the 3rd one...

    Van de Graaff generator is a bit different. As you have a very high potential charge hollow sphere (about 10000 V). It connects to many tubes by resistor chain. Each tube is seperated. The ion source is inside the sphere, then it passes through the tubes, and is accelerated when it passes through gaps.
    The common thing with linac generator is Van de Graaff is linear accelerator
    nice1, we may get a synchotron or linac on monday as van degraaff was in june 04 and a betatron was in the new specimen paper.
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    (Original post by nas7232)
    let me check

    mv^2/r = BQv
    mv/r = BQ
    since e = Q in this case
    v = Ber/m

    t = r/v

    so

    1/f = πr/[Ber/m]
    f = πm/Be

    That's it
    You have to use t=2πr/v .... because it travels 2πr (the circumference)

    that gives v=2πr/t
    into v = Ber/m:
    Ber/m=2πr/t
    Be/m=2π/t
    1/t = Be/2πm
    and 1/t=f

    f= Be/2πm
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    (Original post by habosh)
    maaaaaaaaan you scared me ...I know that and i agree with it 100% I though you meant the diameter gets larger for each cylinder
    lol, i best sort out my wording otherwise i'll lose clarity marks
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    (Original post by endeavour)
    You have to use t=2πr/v .... because it travels 2πr (the circumference)

    that gives v=2πr/t
    into v = Ber/m:
    Ber/m=2πr/t
    Be/m=2π/t
    1/t = Be/2πm
    and 1/t=f

    f= Be/2πm
    yeah that's it, my equation was for a semi-circular journey as this is where the gap in the dees are located.
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    (Original post by nas7232)
    then dont start mixing thing up I suggest just memories that there is a high ac pd.ac means that it's alternating
    AC means alternating current.

    (Original post by nas7232)
    if there is an alternating p.d surely there is an a.c.
    No, I = V/R in a circuit, there is no circuit so there is no current! Or think of it as there is a circuit if you count the insulating air between electrides as a circuit, then R is infinitely high as you don't see any sparks, I is zero.
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    (Original post by mik1w)
    AC means alternating current.



    No, I = V/R in a circuit, there is no circuit so there is no current! Or think of it as there is a circuit if you count the insulating air between electrides as a circuit, then R is infinitely high as you don't see any sparks, I is zero.

    why did you qoute a bit from habosh and it says nas7232 onit loll
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    lol I copied and pasted yuor quote cos I couldnt quote two people at once, forgot to change the name
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    (Original post by mik1w)
    AC means alternating current.



    No, I = V/R in a circuit, there is no circuit so there is no current! Or think of it as there is a circuit if you count the insulating air between electrides as a circuit, then R is infinitely high as you don't see any sparks, I is zero.
    It is 100% an a.c mate, i don't know how to explain it to you. But my teacher clearly stated to me that i should write this in the exam. Best thing to do is read up in a couple books onit to find a better reason why it is an a.c otherwise you may lose marks in the exam.
 
 
 
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