This makes a good occasion to review the relationships between electric voltage, energy, and electric field.
Voltage is energy per unit charge or electric field times distance.
Electric field is force per unit charge. One can get to the idea of voltage by first integrating over distance, to get energy, and then differentiating with respect to charge or by first differentiating with respect to charge, to get electric field, and then integrating over distance. Both paths lead to the same concept. Depending on class interest, we can see why the capacitance of a sphere is proportional to radius with such a simple proportionality constant. Integrating the electric field of a point charge from the surface of the sphere to infinity produces the require relationship.