Answer:
ΔE / E = ΔV / V + Δd / d
Explanation:
The electric field and voltage are related by the expression
E = V / d
The uncertainty of the field is
ΔE / E = ΔV / V + Δd / d
We see that the uncertainty of the field must be added the uncertainty of the distance that in the measure of the different potential has no effect.
The only case in which the uncertainties are equal is if the distance measurement has no uncertainty, or the separation of very high