Recent content by nosmas

I was reading through an example question calculating the electric field in a solenoid and it made an assumption that the radial electric field must be equal to zero because there is no excess charge in the system. I don't understand when this is true or even why it is true, any suggestions...

That makes sense so if I was asked to find the E field using gauss's law for r<=R would I just use E=q/(area*epsilon) but how would I know what q enclosed is?

Homework Statement Using integration calculate the total charge on the sphere radius R Volume charge density at the surface of the sphere p0 p = p0r/R I started with dq = 4*pi*r^2*dr*(p0r/R) but i am not sure how to integrate (in terms of what variable I would assume r=0 to...

I should be using σ for the surface charge density I am just not sure how to incorporate it. So the E field on the hemisphere is equal to the sum of infinetly many rings of charge? I understand that the width of the ring is Rdθ and the radius of the ring is R cos(θ) so the area of the...

Equation 23-10 is dE = k*(dQ/r^2) What I am struggeling with is how the distance to the point of interest z = rcos(theta) and how they came up with the charge on the ring?

My teacher explained a problem of a hemispherical shell in class but i don't understand what he is doing. http://img116.imageshack.us/img116/7656/naamloos27mf.gif

Calculationg the electric field of an insulating sperical shell using integration? Homework Statement We are asked to calculate the electric field at the center of an insulating hemispherical shell with radius R and a uniform surface charge density using integration. Homework...