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    This was a question i got in the cie exam today. Cant quote the question exactly but i can remember the question (If you can recall it better than me feel free to correct me). A resistor Y has the diameter D and length L. A resistor Z has the diameter 2D and length L. Calculate the ratio of the drift velocity Resistor Y drift velocity/ Resistor Z drift velocity. I calculated it and got 4.
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    Hello, I've moved this to physics for you.

    I'm not entirely sure which exam you have taken, but there are lots of exam discussion threads here: http://www.thestudentroom.co.uk/forumdisplay.php?f=372 so you might be able to find what you're looking for there.
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    (Original post by Paranoid_Glitch)
    This was a question i got in the cie exam today. Cant quote the question exactly but i can remember the question (If you can recall it better than me feel free to correct me). A resistor Y has the diameter D and length L. A resistor Z has the diameter 2D and length L. Calculate the ratio of the drift velocity Resistor Y drift velocity/ Resistor Z drift velocity. I calculated it and got 4.
    I think that Z had diameter 2d and length 2l and, as speed is proportional to length and inversly proportional to area (or square of diameter), then v(y)/v(z) = 1/[2*(1/2^2)]=1/[2*(1/4)]=1/[1/2]=2
    Not 100% sure, though.
    EDIT: the answer is actually 4 as length does not affect drift velocity.
    Do you remember how many marks this was worth?
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    For the last ratio, power dissipated in Y/power dissipated in Z , did you get 2?
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    (Original post by olmomiau)
    For the last ratio, power dissipated in Y/power dissipated in Z , did you get 2?
    I think so, i remember it being the same as the resistance ratio.
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    (Original post by Paranoid_Glitch)
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    I see. You have posted the electricity question here, haven't you? are the giving answers not helpful for you? I am trying to solve your question, even if it lasts a bit. Hope to find it out for you.
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    (Original post by Kallisto)
    I see. You have posted the electricity question here, haven't you? are the giving answers not helpful for you? I am trying to solve your question, even if it lasts a bit. Hope to find it out for you.
    Sorry about that, but thanks.
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    (Original post by Paranoid_Glitch)
    Sorry about that, but thanks.
    You have written that you got 4 as the ratio. Would you like to write your calculations down, please? hope to get a picture by seeing your steps.
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    (Original post by Kallisto)
    You have written that you got 4 as the ratio. Would you like to write your calculations down, please? hope to get a picture by seeing your steps.
    Okay. Hopefully it is readable.

    FIRST PART: Name:  Untitled.jpg
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    (Original post by kallisto)
    you have written that you got 4 as the ratio. Would you like to write your calculations down, please? Hope to get a picture by seeing your steps.
    second part

    Name:  part 2.jpg
Views: 199
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    (Original post by Paranoid_Glitch)
    second part

    Name:  part 2.jpg
Views: 199
Size:  75.9 KB
    SO, I hope that I have found a way to calculate the ratio. Hope that you understand my steps, as I am not able to write in latex. Here it is:

    I = Q/t = n*A*e*(L/t); t = D/vd
    => I = n*A*e*(L/(D/vd))

    Iy : Iz = n*A*e*(L/(D/vd)) : n*A*e*(L/(2D/vd) = L/(D/vd) : L/(2D/vd) = 1 : 1/2 = 2

    If it is confusing you too much, I am trying to write my steps in latex.
 
 
 
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