The winding a has Na turns and carries a current Ia. It produces a magnetic intensity in the core h- ala 2丌 The winding b is used to measure the flux passing through Since d= bs, the winding b measures the magnetic field b as well Thus for a value h from a, there is a corresponding value B from 6. We can plot the function B=B(H) as shown in Fig. 14-5 for various materials