Use the result
that the field due to P is given by the expression [Eqs (5 7) and (5 8)]:
0
P
P
3
4
r
µ
π
= −
m
B
     (on the normal bisector)
0
P
P
3
42
r
µ
π
=
m
B
     (on the axis)
where mP is the magnetic moment of the dipole P