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anap40
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Homework Statement
A square of side a located in the x-y plane and centered on the origin carries a total
charge Q uniformly distributed over its circumference.
(a) What is the electric eld at any point on the z-axis? How does the eld behave far from
the square?
(b) An electron constrained to move along the z-axis near the center of the square is seen to
exhibit small oscillations above and below the plane of the square. What is the frequency of
these oscillations? (assume Q is positive)
Homework Equations
So for the first part I got E=KQz/[(x^2+y^2)^2sqrt((x^2+y^2)^2+(a/2)^2)]
For the behavior far from the square I made z>>a/2 and got back E=kQ/b^2
I am stuck on part B. The force is just q times the field, and z<<a/2 but I don't know where to go to get the period.
I appreciate any help.