What is the Potential at the Origin for a Uniformly Charged Semi-Circle?

[brad sue]

I have this problem for homework and I would like to check my work:

Charges are distribyted with uniform charge density (lambda)along a semi circle of radius R, centered at the origin of a coordinate system.
What is the potential at the origin?

I did this:
dV=k*dq/R where k=1/4*pi*(epsilon 0)


but dq=(lambda)*R*d(theta) theta is the small angle between two position on the semi circle.

pi
then V =| k*(lambda)*R*d(theta) / R (integral from 0 to pi)
0
After computation I found: V=(lambda)/(4*epsilon 0)

Thank you

 

[Galileo]

Looks ok.
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