(a) State Ampere's circuital law. Use this law to obtain the expression for the magnetic field inside an
air cored toroid of average radius V, having turns per unit length and carrying a steady current I.
(b) An observer to the left of a solenoid of N turns each of cross section area 'A' observes that a steady current I in it flows in the clockwise direction. Depict the magnetic field lines due to the solenoid specifying its polarity and show that acts as a bar magnet of magnetic moment m = NIA.