Answer
(a) $1.9KV$
(b) increase
(c) $3.8KV$
Work Step by Step
(a) We know that
$\Delta V=E\Delta s$
We plug in the known values to obtain:
$\Delta V=(3.0\times 10^6)(0.025in\times 0.0254m/in)$
$\Delta V=1.9KV$
(b) We know that the electric potential difference is directly proportional to the separation between the electrodes. Thus, if the separation is increased then the potential difference will increase.
(c) We know that
$\Delta V=E\Delta s$
We plug in the known values to obtain:
$\Delta V=(3.0\times 10^6)(0.050in\times 0.0254m/in)$
$\Delta V=3.8KV$