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plat911
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Homework Statement
A charge Q is distributed evenly on a wire bent into an arc of radius R, as shown in
the figure below.What is the mathematical expression that describes the electric field
at the center of the arc (point P indicated) as a function of the angle θ? Sketch
a graph of the electric field as a function of θ for 0 < θ < 180.
I added the figure for the question as an attachment.
The Attempt at a Solution
lambda=Q/pi R
dE= kdQ/R^2
dE= (kdQ/R^2) cos θ
dQ=lambda dl
dl= Rd theta
dQ=lambda R dθ
dE=(k[lambda R d θ]/R^2)cos θ
E=(k lambda R cos θ/R^2)d θ(from pi/2 to -pi/2)
E=k lambda/R cos θ dθ
E=k lambda/Rsin θ
E=k lambda/R[sin(pi/2)-sin(-pi/2)]
E=k lambda/2R
E=k(Q/piR)/2R=2kQ/piR^2
E= 2kq/piR^2
Is this right? I used K for 1/4pi(E) to make it easier to type.
Also i am kind of lost on what is expected for the sketch.