What is the maximum possible potential (relative to infinity) of a metal sphere of 10 cm radius in air? What is the maximum possible potential of a metal sphere of only 1 mm radius? These results hint...

What is the maximum possible potential (relative to infinity) of a metal sphere of 10 cm radius in air? What is the

maximum possible potential of a metal sphere of only 1 mm radius? These results hint at the reason why a highly charged

piece of metal (with uniform potential throughout) tends to spark at places where the radius of curvature is small or at

places where there are sharp points. Remember that the breakdown electric field strength for air is roughly 3 × 106 V/ m.