A semi-infinite solenoid (conce ntric with the negative z-axis) has cross sectional area A = R 2 , n turns per unit length of a

A semi-infinite solenoid (conce ntric with the negative z-axis) has cross sectional area A = πR², n turns per unit length of a wire with current I , and magnetic moment per unit length m = nIA. When A → 0 and N →∞ with m fixed, Application 11.1 showed that the agnetic field outside this solenoid (i.e., excluding the negative z-axis) is

Use the field inside an infinite solenoid to approximate the field Bin inside a semi-infinite, finite-area solenoid.
Show that when A → 0, B_in is confined to the negative z-axis and ∇ · B_in = −μ₀mδ(r). This guarantees that ∇ · (B_in + B_out) = 0 as it must. 

Show that lim

Bout Hom f - 1 4 2