Challenge: two electromagnetic problems

[wine9]

(a) When there is a phase-to-neutral fault on a transmission line, will the existence of the neutral wire increase or decrease the magnetic field under the transmission line? Why?

(b) Assuming that the whole space consists of an upper half space with soil resistivity r1 and a lower half space with soil resistivity r2, assuming further that a point current source, I, is located h meters away from the soil interface in the upper space, find the Earth potential at the image position of the point source in the lower space

 

[arcnets]

Hi wine9, sorry I'm completely lost at this.

(a)If the neutral line doesn't exist, then how can you have a phase-to-neutral fault?
(b)I think this is a refraction (not reflection) problem and so the image should be in the upper space.