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Homework Help: What is the charge carrier density in the conductor

  1. Apr 7, 2010 #1
    The Hall voltage across a 0.800-mm-thick conductor in a 1.30 T magnetic field is 3.2 uV when the current is 12.0 A.

    What is the charge carrier denisty in the conductor (in m-3).

    I was using the equation Vh=IB/ned
    where Vh is the Hall voltage
    I is the current
    B is the magnetic field
    n is the charge-carrier density
    e is the charge of an electron
    and d is the thickness

    I rearranged to get n=IB/Vhed
    and evaluated to get 3.806*1025m-3

    But this came up wrong on the assignment and it looks like an unreasonable answer. I think I need additional values but basically this entire question is really confusing me.

    Thanks for the help!
    Last edited by a moderator: Apr 7, 2010
  2. jcsd
  3. Apr 7, 2010 #2
    Please show us what numbers you used, and try to keep everything in SI units. Because I get a different answer than you when plugging in the numbers you gave.
  4. Apr 7, 2010 #3
    I used the numbers I provided so:
    I=12.0 A
    B= 1.3 T
    e= 1.6*10^(-19) C
    V= 3.2*10^(-6) V
    d= 0.8 mm (I left it because those are the units that the answer is in- but I'm guessing now that that is probably wrong).

    What did I miss that is wrong in the calculation?
  5. Apr 7, 2010 #4
    The units the answer is in is meters, not millimeters. So d = 8*10^-4 m.
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