An=200-turn solenoid having a length of l=25 cm and a diameter of 10 cm (r=5 cm) carries a current of i= 0.30 amp. (a) what is the magnetic field near the center of the solenoid? (b) what is the magnetic flux through an annular ring having an inside diameter of d=2.0 cm and an outside diameter of d=8.0 cm if the plane of the ring is perpendicular to the axis of the solenoid? solve using variables first and plug numbers at the end. hint: calculate the field of one loop as a function of z and then add up all the loops.