Electric Charges and Fields

  • Thread starter LampMan
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  • #1
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Homework Statement


two charged spheres 4 cm apart attract each other with a force of 1.2x10^-9 . determin the magnitude of the charge on each if one has twice the charge (of the opposite sign) as the other.


Homework Equations



Fe = KQq/r^2

The Attempt at a Solution



well you are only given Fe and r, plus the info that Q is = to (2)q and k = 9.0x10^9 so im stumped after this step

1.2x10^-9 = (9.0x10^9)(2)qq/16
 
Last edited:

Answers and Replies

  • #2
kuruman
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In your equation everything is a number except for q. Can you solve it for q? Also, you forgot to convert cm to meters.
 
  • #3
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could it possibly be that im using the wrong equatiom? and should be using E(force intensity) = kq/r^2 instead of coulombs law??

edit: yes i forgot to convert haha good call..but yea the fact that im finding two charges throws me off...so would just solving for one q give me the charge im looking for, then just double it to get the 2nd charge?
 
  • #4
kuruman
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Correct. Find q then double it. It is that simple.
 
  • #5
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aha well ive mised 2 of 2 classes on this unit so i cant believe it was that easy now that i see it ahhh well thanks alot
 

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