Problem 3.279

When a ball made of uniform magnetic is introduced into an external uniform magnetic field with induction \(\mathbf{B}_{0}\), it gets uniformly magnetized. Find the magnetic induction \(\mathbf{B}\) inside the ball with permeability \(\mu\); recall that the magnetic field inside a uniformly mag netized ball is uniform and its strength is equal to \(\mathbf{H}^{\prime}=-\mathbf{J} / \overrightarrow{3},\) where \(J\) is the magnetization.