Question

What is the relationship between the electric field E and the electric potential V between the plates of the capacitor?j

Answer 1

The relationship between the field $E$ (assume uniform) and potential $V$ between the plates of the capacitor is the following (see https://www.nikhef.nl/~h73/kn1c/praktikum/phywe/LEP/Experim/4_2_01.pdf):

$$E = \dfrac{V}{d}$$

where $d$ is the distance between plates.

Answer. $E = V/d$.