Consider a thin spherical shell of radius R with its center at the origin, carrying uniform positive surface charge density. The variation of the magnitude of the electric field and the electric potential V(r) with the distance r from the center, is best represented by which graph?

Outside the charged spherical shell, the electric field E is given by E = kq/r², where k is Coulomb's constant, q is the total charge of the shell, and r is the distance from the center. The electric potential V is given by V = kq/r. Inside the charged spherical shell, the electric field E(r) is zero, and the electric potential V(r) is constant and equal to the potential at the surface of the shell, which is V = kq/R.