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Calculate the component of the electric field

  • Thread starter nokia8650
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  • #1
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http://img367.imageshack.us/img367/5459/69671206ju9.th.jpg [Broken]

See image above. Point charges A, of +2.0nC, and B, of –3.0 nC, are 200mm apart in a vacuum, as shown by the figure. The point P is 120mm from A and 160mm from B.

(i) Calculate the component of the electric field at P in the direction AP.
(ii) Calculate the component of the electric field at P in the direction PB.

The markscheme uses E= kQ/(r^2)

where k = 1/4*pi*epsilon

However, for part (i), uses only the 2nC charge, while uses only the -3nC charge for part ii - can someone please explain why this is the case.

Thanks
 
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Answers and Replies

  • #2
Doc Al
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In what direction is the field at P due to A? Due to B?
 
  • #3
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ahh yes, i understand now, thanks
 

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