Where is the electric field closest to uniform? inside a circle described by a point charge at its center between parallel plates of equal charge and equal magnitude inside a circle described by identical, evenly-spaced point charges around the circumference between parallel plates of equal charge and opposite magnitude

1. Inside a circle described by a point charge at its center will not be uniform field as a point charge field will change with distance where as we move away the field strength will go down.

2. between parallel plates of equal charge and equal magnitude will have zero electric field because both plates are of same charge so electric field of both plates will cancel each other.

3. inside a circle described by identical, evenly-spaced point charges around the circumference field will be zero as all charges are distributed uniformly and they cancel the field effect of each other.

4. between parallel plates of equal charge and opposite magnitude field will be nearly uniform as the two charges are opposite in nature and equal in magnitude so the effect will be added.

So answer of the above will be between parallel plates of equal charge and opposite magnitude

this means that the temperature of both substances will be equal