Question

which graph best represents the potential as a function of distance r from charge q?

Answer 1

two charge +q₁ and +q₂ placed on x - axis at position A and B as shown in figure.

we have to identify the graph which represents the potential as a function of distance r from charge q₁.

solution : let d is the distance between +q₁ and -q₂.

now potential at r distance from charge +q₁, V = kq₁/r + k(+q₂)/(d - r)

= k [q₁/r + q₂/(d - r)

at r = 0 and r = d (i.e., AB)

V = ∞

means at two points r = 0, d graph can't touch vertical line.

between A and B, potential increases when observations point shift to charges but at the middle point, potential will be minimum.

this criteria only explained in graph 2

Therefore option (2) is correct choice.