Finding current through a surface (electrostatics model)

I have created a project in comsol 3.4 where I am have a material, with electrodes (contacts) at each end.

I've created a model, and using the electrostatics model, I've defined relative permittivity for all the subdomains. In boundary settings I have set a voltage to one contact, while the other is set to ground. I need to know the electric power running through my material, so I guess the best way would to find out the current and then use Power = V*I .

Can anyone shed a light on how one goes about finding the current running through a surface. Or are there better ways to find the power running through my sample?

I also have access to comsol 4.3b if things are any easier there. I'm only using 3.4 since I'm used to that one.


Kind regards
Frímann