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Homework Help: How should I approach this question?

  1. Jan 18, 2006 #1
    A K+ ion and a Cl- ion are directly across from each other on opposite sides of a membrane 7.9 nm thick. What is the electric force on the K+ ion due to the Cl- ion? Ignore the presence of other charges.


  2. jcsd
  3. Jan 18, 2006 #2
    hmmm... do you know coulomb law? [tex]E=\frac{q}{|r_1-r_2|^2}[/tex]
    and [tex]F=qE[/tex]
  4. Jan 18, 2006 #3
    Yes, but all that is given in the problem is "r". How do I find "q"?
  5. Jan 18, 2006 #4
    The q is just the value of -e i think.
  6. Jan 18, 2006 #5


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    HINT: What do the "+" and "-" mean in K+ and Cl-?
  7. Jan 18, 2006 #6
    Ohhh, ok. Thanks a bunch guys.
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