a) amplitude of the fundamental curve = 1.27 * flux density in the air gap * cosine (phase angle/2)
b) amplitude of the fundamental curve = 1.27 / flux density in the air gap * cosine (phase angle/2)
c) amplitude of the fundamental curve = 1.27 * flux density in the air gap / cosine (phase angle/2)
d) amplitude of the fundamental curve = 1/1.27 * flux density in the air gap * cosine (phase angle/2)
