(a) If an isolated conducting sphere 5.0 cm in radius has a net charge of 4.9 μC and if V = 0 at infinity, what is the potential on the surface of the sphere? (b) Can this situation actually occur, given that the air around the sphere undergoes electrical breakdown when the field exceeds 3.0 MV/m?

Part a:  360000 V

Part b: no

Explanation:

Part a:  

V = k q/r = (9^9)* (4.9^-6)/(0.05) = 360000 V  

Part b:

the electric field on the surface of the sphere :

E=k q/r^2

 =3.6 MV/m

therefore the air around the sphere undergoes electrical breakdown

r = ρ x length / area  

ρ = r x area / length  

ρ is in ohm-meters  

in basic units, it is m³kg/s³a²  

i think this is it.