(a) The Ev lines are perpendicular to the plates and uniformevery where betwn the plates. Sketch some of these horiz lines,with the plates vertical. Sorry i diont have draving skill.But you can do it. Follow these.

The plates themselves are equipot surfaces. A conductingsurface is always at the same pot at every point on it.The plate on the left at V = 0 is the firstequipot surface for V = 0.

The second plate at d = 1.70 cm is another equipotsurface with V = 480 V.

We can see from the relation E = ΔV/dfor a uniform field, that ΔV = E.d Thechange in pot is proportional to the displacement.

Hence, the planes parrallel to the plates and at \(\displaystyle{d}_{{1}}=\frac{{1.7}}{{4}}={0.425}{c}{m},{d}_{{2}}={\frac{{{1.7}}}{{{2}}}}={0.85}{c}{m}\) and \(\displaystyle{d}_{{3}}={1.7}\times{\frac{{{3}}}{{{4}}}}={1.275}\ {c}{m}\) are equipot surfaces with \(\displaystyle{V}_{{1}}={120},{V}_{{2}}={240}\) and \(\displaystyle{V}_{{3}}={360}{V}\) respectively.

(b) The field lines are perpendicular to the plates. The equipot surfaces are parallel to the plates. Hence the field lines and equipot surfaces are perepndicular to each other.

The plates themselves are equipot surfaces. A conductingsurface is always at the same pot at every point on it.The plate on the left at V = 0 is the firstequipot surface for V = 0.

The second plate at d = 1.70 cm is another equipotsurface with V = 480 V.

We can see from the relation E = ΔV/dfor a uniform field, that ΔV = E.d Thechange in pot is proportional to the displacement.

Hence, the planes parrallel to the plates and at \(\displaystyle{d}_{{1}}=\frac{{1.7}}{{4}}={0.425}{c}{m},{d}_{{2}}={\frac{{{1.7}}}{{{2}}}}={0.85}{c}{m}\) and \(\displaystyle{d}_{{3}}={1.7}\times{\frac{{{3}}}{{{4}}}}={1.275}\ {c}{m}\) are equipot surfaces with \(\displaystyle{V}_{{1}}={120},{V}_{{2}}={240}\) and \(\displaystyle{V}_{{3}}={360}{V}\) respectively.

(b) The field lines are perpendicular to the plates. The equipot surfaces are parallel to the plates. Hence the field lines and equipot surfaces are perepndicular to each other.