A point charge is placed between two semi- infinite conducting plates ...
Degrees to each other. The charge is placed on the surface of one of the plates. The electric field between the plates is given by:
E = σ/2ε0sin(θ)
where σ is the surface charge density, ε0 is the permittivity of free space, and θ is the angle between the plates.
In this case, the charge is placed on one of the plates, so σ is equal to the charge density on that plate. Let's assume that the charge is positive and placed on the plate with the smaller angle, so the electric field points towards the larger angle.
If the distance between the plates is d, then the electric field at a point between the plates and a distance x from the plate with the charge is:
E = σ/2ε0sin(θ) * x/d
The electric potential difference between the plates is given by:
V = Ed = σx/2ε0sin(θ)
The potential at a point between the plates and a distance x from the plate with the charge is:
V(x) = σx/2ε0sin(θ)
The potential difference between two points, x1 and x2, on the same side of the charge is:
ΔV = V(x2) - V(x1) = σ(x2 - x1)/2ε0sin(θ)
Therefore, the potential difference between two points on the same side of the charge is proportional to the distance between the points. The electric field, on the other hand, is constant between the plates and proportional to the distance from the plate with the charge.
Note that if the charge is negative, the electric field and potential will point in the opposite direction, but the equations will be the same.