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littlebilly91
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Homework Statement
A non-uniformly charged semicircle of radius R=28.0 cm lies in the xy plane, centered at the origin, as shown. The charge density varies as the angle θ (in radians) according to λ = + 5.8 θ, where λ has units of μC/m.
(picture included)
What is the y - component of the electric field at the origin?
Homework Equations
dE=[tex]\frac{dq}{4\pi\epsilon r^{2}}sin\theta[/tex]
where [tex]\epsilon[/tex] = 8.85*10^{-12}
[tex]\theta r = s[/tex]
[tex]\lambda=\frac{q}{s}[/tex]
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The Attempt at a Solution
First I derived [tex](5.8*10^{-6})\theta^{2} r=q[/tex]
and took the derivative [tex]2(5.8*10^{-6}) r \theta d\theta=dq[/tex]
substituted into equation 1
dE=[tex]\frac{2(5.8*10^{-6})}{4\pi\epsilon r}\theta sin(\theta)d\theta[/tex]
Integrated from 0 to pi.
E=[tex]\frac{(5.8*10^{-6})}{2\pi\epsilon r}\int\theta sin(\theta)d\theta[/tex]
The whole integral simplifies down to pi,which cancels out and leaves
E=[tex]\frac{(5.8*10^{-6})}{2\epsilon r}[/tex]
I am getting 1.17*10^{6} N/C for an answer, but it's not correct.
Thanks for the help in advance.
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