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April 20, 2014

April 20, 2014

Posted by **Crystal** on Thursday, February 3, 2011 at 3:31pm.

Part A

Find the magnitude of the net electric force exerted on this charge.

Express your answer in terms of some or all of the variables q, R, and appropriate constants.

Part B

Find the direction of the net electric force exerted on this charge.

Express your answer as an integer. (in degrees counterclockwise from the positive x axis).

- Physics -
**bobpursley**, Thursday, February 3, 2011 at 4:01pmThis is a rather simple problem.

Do it with symettry.

First, find the E at the center if the all 12 charges are symettrical about the circle (wont it be zero?).

Next, then consider what if you put a charge at one position which is opposite, making a net charge of zero at that position.

Add then E from this added "virtual" charge. E=k(-q)/R^2 the negative sign means it is in the opposite direction as the original E.

Net E=kq/r^2, the E points toward the replaced charge

- Physics -
**Crystal**, Thursday, February 3, 2011 at 4:13pmE=kq/r^2 doesn't seem to be the correct answer for Part A.. help?

Ofcourse, for part B, 0 degrees makes sense and is correct as you have explained.

- Physics -
**Crystal**, Thursday, February 3, 2011 at 4:15pmNever mind, got it!

Thanks!!

- Physics -
**Anonymous**, Thursday, February 3, 2011 at 4:50pmi hv the same question i understand part b but i am getting wrong answer for part a, what was the equation you used crystal?

- Physics -
**Anonymous**, Thursday, February 3, 2011 at 4:50pmi hv the same question i understand part b but i am getting wrong answer for part a, what was the equation you used crystal?

- Physics -
**Jim**, Thursday, February 3, 2011 at 4:51pmi hv the same question i understand part b but i am getting wrong answer for part a, what was the equation you used crystal?

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