The diagram shows a wire connected to the Earth (conductivity E ) through a perfectly conducting

Question:

The diagram shows a wire connected to the Earth (conductivity σ_E) through a perfectly conducting sphere of radius a which is half-buried in the Earth. The layer of earth immediately adjacent to the sphere with thickness b − a has conductivity σ₂. Find the resistance between the end of the wire and a point deep within the Earth (taken as infinitely large).