Question

determine the potential difference between two charged parallel plates that are .10 cm apart and have an electric field strength of 12V/cm

Answer 1

The potential difference between two parallel plates is related to the electric field intensity by
$\Delta V = Ed$
where
$\Delta V$ is the potential difference
E is the electric field intensity
d is the distance between the two plates.

In our problem,
$d=0.10 cm$
and 
$E=12 V/cm$
so we can calculate the potential difference as
$\Delta V= Ed = (12 V/cm)(0.10 cm)=1.2 V$