1. The problem statement, all variables and given/known data griffiths 6.13: Suppose the field inside a large piece of magnetic material is Bo, so that Ho = (1/uo)Bo - M. Now a small spherical cavity is hollowed out of the material. Find the field at the center of the cavity, in terms of Bo and M. Also find H at the center of the cavity, in terms of Ho and M. 2. Relevant equations closed integral (H * dl) = Ifenc 3. The attempt at a solution Well since I thought that the free current inside the cavity would be zero, that made H also zero. Because H was zero, M = 1/uo B. So M = uoHo / Bo. Therefore B = uo2Ho / Bo And H = 0 = uoHo / Bo - M. I guess I'm just confused because I'm not real sure how to approach the problem; this was all I could think of. btw, a link to the various symbols would obviously be welcomed.