I'm trying to solve the following problem but I have some doubts.
I have a disk of radius $R$ with charge $Q$ (positive) and, at distance $d$, an uncharged conductor (of radius $R$ as well). Both are centered at the same axis.
Supposing $R$ is very big compared to the considered distances, I'm asked about the electric field $\vec E$ between the disk and the conductor, inside the conductor, and above it.
I know, since $R$ is big, I can approximate the disk as an "infinite" plane, so $\vec E$ will be uniform. In that case, it's easy to calculate the field caused by the disk alone. But total $\vec E$ will be $\vec E_{\text{disk}} + \vec E_{\text{conductor}}$ and I can't figure out how to find this last one.
Here's what I'm talking about if it's not so clear (my english may not be very good).
Any help would be appreciated.