By (9.27), for NEO | H → d e m a g | = M r = 10.3 × 10 5 A / m, so an additional H ext = H c – H demag = (16.0 − 10.3) × 10 5 = 5.7 × 10 5 A/m, or B = 0.72 T, must be applied opposite to the magnetization to demagnetize (in this case, to reverse) the magnetization. This is very large; it is difficult to accidentally demagnetize a thin ...