Ok i'm realllly unsure about this!(adsbygoogle = window.adsbygoogle || []).push({});

If a spherical cavity of radius 3.66cm in a piece of metal (kind of cube, but not a perfect cube) has a charge of +Q at it's centre and there is a point P1 located half way between the spherical cavity and it's surface and a point P2 located in the metal piece , use gauss Law to find the electric field at

a) Point P1

b) point P2

a) This is fine for me

Let e0 = permittivity of free space epsilon 0

e0 SurfaceIntegral (E dA) = q

e0 E (4 pi r^2 ) = q

E = kq /r^2

which is coulomb's law derived! and just plug and away i go!

b) But for point P2

err can i actually use a spherical surface here??

as in do the same thing as before but use a bigger value for r i.e. radius of sphere + distance of sphere to point P2

appropriate? or not?

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# Homework Help: Still more problems with Gauss Law

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