Electric Field

  • #1

Homework Statement


Screenshot2011-01-28at123342PM.png



Homework Equations


E=ke*q/r2


The Attempt at a Solution


See screenshot. The angles are correct, however I can't get the equation right for either part. I understand they should be different since one is force and the other electric field, I thought that should be the electric field solved and simplified.

Not sure how to put in equations on here, so I'll do my best.
before simplification, I had for the i component:
ke3q/a2+sqrt(2)/2*ke4q/a2

and for the j component:
ke5q/a2+sqrt(2)/2*ke4q/a2


where have I gone wrong? the sqrt(2)/2 is cos(45) and sin(45) to get the components of the Bq in the drawing. Not sure what the problem is. I can do these fine with numbers so maybe I just am not putting it into the computer right. suggestions?
 

Answers and Replies

  • #2
Delphi51
Homework Helper
3,407
11
Ei = ke3q/a²+sqrt(2)/2*ke4q/a² = kq/a²[3 + 2√2]
In the screenshot, you have √2 when you should have 2√2.
Same in the j part.

Use F = q*E to get the force - same expression, just square the q.
 

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