Electric Potential and Electric Energy

  • #1

Homework Statement


Consider point a which is 65 cm noth of a -2.8μC point charge, and point b which is 80 cm west of the charge. Determine (a) Vba=Vb-Va, and (b) Eb-Ea (magnitude and direction)


Homework Equations


k=9x10-9
V=kQ/r
V=kQ(1/rb-1/ra)
E=kQ/r2
E=kQ(1/rb2-1/ra2)


The Attempt at a Solution


(a) Vba=Vb-Va
=kQ(1/rb-1/ra)
=(9x10-9)(-2.8x10-6)(1/0.8-1/0.65)
=7.269x10-15 V

(b) Eb-Ea
=kQ(1/rb2-1/ra2)
=(9x10-9)(-2.8x10-6)(1/0.82-1/0.652)
=2.027x10-14 N/C

I may have mistakes. I wonder if it's right. So I found the magnitude for (b) but I'm not quite sure about the direction (since it has a negative magnitude)? :shy:
 
Last edited:

Answers and Replies

  • #2
Doc Al
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(b) Eb-Ea
=kQ(1/rb2-1/ra2)
=(9x10-9)(-2.8x10-6)(1/0.82-1/0.652)
=2.027x10-14 N/C

I may have mistakes. I wonder if it's right. So I found the magnitude for (b) but I'm not quite sure about the direction (since it has a negative magnitude)? :shy:
Realize that Eb and Ea are vectors. You must subtract them as vectors.
 
  • #3
So I have to separate them to their own X and Y components??
 
  • #4
Doc Al
Mentor
45,093
1,397
So I have to separate them to their own X and Y components??
Sure, that's one way of doing it.
 

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