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Homework Help: 2 problems in Dimensional analysis

  1. Dec 27, 2006 #1
    1. The problem statement, all variables and given/known data

    The number of particles crossing per unit area perpendicular to X-axis in unit time is N = -D (n2 – n1)/(x2 – x1)
    Where n1 and n2 are number of particles per unit volume for the value of x1 and x2 respectively. What are the dimensions of diffusion constant D?

    Can anyone please tell me how to start this problem? Thanks
  2. jcsd
  3. Dec 27, 2006 #2
    The first you need to do is know the units of each variable in the equation. So, the two n-terms, the two x-terms and the N at the left side.

    Then, put all these variables at one side and D at the other side of the equality. Replace all the variables by their associated unit and you are done.

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