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Homework Help: Width of Slicon Strip?

  1. Sep 23, 2007 #1
    1. The problem statement, all variables and given/known data

    A strip of doped silicon 270 µm wide contains 9.1E22 conduction electrons per cubic meter and an insignificant number of holes. When the strip carries a current of 110 µA, the drift speed of the electrons is 44 cm/s. What is the thickness of the strip?

    2. Relevant equations


    Where I is current, n is electrons per volume, A is cross sectional, v is drift velocity

    3. The attempt at a solution

    I've plugged into the equation above the variables given in the problem and solved for area. But how to find thickness, given the width? I think there's a missing link somewhere.
  2. jcsd
  3. Sep 23, 2007 #2
    Think about it: which area is that?
  4. Sep 23, 2007 #3
    It's the surface area of the strip. I've thought about it. I have the width and the surface area but I cannot solve for thickness.
  5. Sep 23, 2007 #4


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    Science Advisor
    Homework Helper

    No it's the cross sectional area of the strip - does this help you find the thickness?
  6. Sep 23, 2007 #5
    Yes, just divide that by the width. Thanks!
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