chapter 29 pt 3

29.55

55. || The toroid of FIGURE P2955 is a coil of wire wrapped around a doughnut-shaped ring (a torus). Toroidal magnetic fields are used to confine fusion plasmas. a. From symmetry, what must be the shape of the magnetic field in this toroid? Explain. b. Consider a toroid with N closely spaced turns carrying current I. Use Ampere's law to find an expression for the magnetic field strength at a point inside the torus at distance r from the axis. c. Is a toroidal magnetic field a uniform field? Explain. FIGURE P2955 FIGURE P2956