- #1
yeshuamo
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Homework Statement
A thin sheet in the shape of an annular semicircle has a positive surface charge density +σ as shown. What is the electric field at point P?
Here is an illustration of the problem:
http://postimg.org/image/630bpqwan/
Homework Equations
Gauss's Law:
φ=Qenclosed/ε0
φ=∫E⋅dA
Qenclosed=ε0*∫E⋅dA
Coulomb's Law:
E=(1/(4πε0))(Σq/(r2))
The Attempt at a Solution
If I draw a gaussian surface somewhere between the point P and the radius a, the charge enclosed would be zero. Can I assume that this would mean that the electric flux through that surface is zero, and, by extension, the electric field experienced at point P is zero, too?
If I'm wrong about the Gauss's law approach, should I instead use a Coulomb's law approach and integrate the electric field generated by the semicircular sheet, minus the electric field generated by the semicircular cavity?
Thank you.