he energy product indicates the energy that a magnetic material can supply to an external magnetic circuit when operating at any point on its demagnetization curve, measured in MGOe or J/m3. The product of magnetic induction Bd for ordinates and magnetic field Hd for abscissa is defined as energy product and denoted as (BdHd). The energy product of a permanent magnet that we commonly refer to is the maximum value (BH)m that can be obtained on the demagnetization curve (refer to 9 Q).

As discussed in 5Q, Br ³ m0Hcb, we can intuitively known that the maximum product (BH)m must be smaller than Br2/4.