Solving Magnetic Field Problems: Cylinder of Permanent Magnetization

[Dassinia]

Hello, I have an exam Tuesday and I'm solving the problems of previous years :

Homework Statement

Consider a disk of radius a and length h of permanent magnetization M = Moz parallel to h.
a/ what are the units of Mo ?
b/Find the magnetic current density J_b inside the cylinder and the curface current density K_b on the three surfaces.
c/ Write boundary conditions of B and H for the three surfaces.
d/ Plot field lines for B and H everywhere.

Homework Equations

K_b=Mxn^
J_b=∇xM

The Attempt at a Solution

a/ A/m
b. Inside the cylinder, the magnetization is constant so
J_b=∇xM =0
I don't get what they mean by the three surfaces, inside the cylinder, outside and ?

Thanks !

 

[marcusl]

The 1) top and 2) bottom surfaces of the disk, and 3) the cylindrical surface at radius a.