Find the current that flows (electric feild)

[leonne]

Homework Statement

2 spheres at a potential diff V what current flows from one to the other

Homework Equations

I=$$\int$$j.da

The Attempt at a Solution

My question is about finding the electric field. I thought it would be E=$$\sigma$$/$$\epsilon$$ but they have it has E= Q/4$$\pi$$r²$$\epsilon$$ why is it? Then they find the potential difference and plug that in for Q.
In a similar problem but with cylinders, they do what I thought. The get E=$$\lambda$$/$$\epsilon$$2$$\pi$$s

 

[NateD]

. I'm confused about why it is different for spheres and cylinders. The answer for the question is I= V/R where R is the resistance between the two spheres. To find R, we use Ohm's law, R = V/I, and so I = V/R.