To develop this problem it is necessary to apply the concepts related to a magnetic field in spheres.
By definition we know that the magnetic field in a sphere can be described as

Where,
a = Radius
z = Distance to the magnetic field
I = Current
Permeability constant in free space
Our values are given as
diameter of the sphere then,

Thus z = a



Re-arrange to find I,



Therefore the current at the pole of this sphere is 
Explanation:
Mechanical Advantage (MA)
MA=d1d2=FoutFin ; d1 is the distance of effort, d2 is the distance the object is moved
If the two waves have the SAME FREQUENCY and are exactly
out of phase (180° apart), then the resultant wave will have the
same frequency and an amplitude of 1 unit.
If the two waves do not have the SAME FREQUENCY, then their
relative phase is meaningless.
Look kid, this question has been up for 16 hours think its time to let it go......... hoped i helped. ✔verified✔