2. A brushless d.c. motor has the cross-section shown in Fig. 4.15 with r, = 30 mm 1.8 mm.g=0.8 mm, and axial length 1= 35 mm. Slotting is neglected and a single full-pitch stator coil is shown with 30 turns. The ceramic magnet has B.=0.35 T. Pres=1, and H=278 KA/m. The current in the stator coil is zero. (a) Sketch the magnetic field set up by the magnet, by drawing 10 flux lines. (b) Sketch the variation of the radial component of airgap flux-density (B, y around the inside of the stator, from 0 to 360 (c) Draw an equivalent magnetic circuit and use it to calculate the flux crossing the 2. A brushless d.c. motor has the cross-section shown in Fig. 4.15 with r, = 30 mm 1.8 mm.g=0.8 mm, and axial length 1= 35 mm. Slotting is neglected and a single full-pitch stator coil is shown with 30 turns. The ceramic magnet has B.=0.35 T. Pres=1, and H=278 KA/m. The current in the stator coil is zero. (a) Sketch the magnetic field set up by the magnet, by drawing 10 flux lines. (b) Sketch the variation of the radial component of airgap flux-density (B, y around the inside of the stator, from 0 to 360 (c) Draw an equivalent magnetic circuit and use it to calculate the flux crossing the