Recent content by SilverGirl

Does anyone know how they got the 28 pairs?

Anyone?

Yeah it doesn't say where the charges are coming from. 8*7/2 ... where does the 7/2 come from? How are you getting 28 pairs? 12 sides of a cube? Aren't there only 6?

Homework Statement How much work is required to assemble eight identical charged particles, each of magnitude q, at the corners of a cube of side s? Homework Equations W=deltaU delta U = kQq/r The Attempt at a Solution I've come up with those equations, and was trying to plug...

After you left, I think I may have got it. Just had to look at the example problems for the 15th time I guess. Hopefully it's good, because I was able to prove Ey for sure. Thanks very much for all your help! :D

but it doesn't say if there is a positive or negative charge? Or does this have to do with r+ and r-?

So how do you know which way the electric field vector is pointing?

Umm..I did a completely different question with the flux. This entire question was in my original post.

umm...i did electric flux where R>d...i am not finding one with electric field

the vectors represent the charge distribution, whether positive or negative, depending on the r vector. right?

On my prof's thing, he chose a point P near the top right of the cavity. He had r+ and r- pointing to them, away from the center. So, sorry about the confusion, I have those drawn in, as I used the diagram he made. The obvious solution is not coming to me though, and I feel completely lost...

I have drawn it. I have made points at the centre of both the sphere and the cavity. Choose any other point? Do you mean any point inside the cavity? Or a point outside the circle? Draw the vectors involved? You mean E and A right? If so, it says prove the E component vectors are...

Anyone?

Gauss' Law - Sphere with spherical cavity - Please help Homework Statement A sphere of radius 2a is made of nonconducting material that has a uniform volume charge density . (Assume that the material does not affect the electric field.) A spherical cavity of radius a is now removed from the...

I have done derivatives before, but never antiderivatives before and am not sure. Just giving a wild guess would be, x ?