i don't want to be a bummer, but UCSD's physics gre cutoff is 50%. and it's like 3rd down the list of UC schools for physics grad programs. they don't explicitly say that they have a cutoff, but i had a professor friend ask colleagues there for me, and that's what they told him. =/
i have the dimensions of the block. it has a 25 square cm face, is 12 mm thick and the electrons are evenly distributed in a 2 mm thickness 6 mm below the surface. now that i think about it, maybe it won't be easy to determine E. i guess I'm missing the connection between a known volume...
I'm guess I'm just having trouble with this. you're clearly right about the free charge density inducing a bound charge density within the volume injected with electrons (easy to find knowing the free charge density and the relative permittivity). i can find E outside of the electron volume...
i'm working through a homework problem. it has us jump through a few hoops. the premise is that a bunch of electrons are injected into a block of lucite (relative permittivity is supplied). the electrons are all concentrated in a given volume within the block. it asks us for the volume...