A toroidal solenoid has a radius R = 0.5 m and a cross-sectional diameter equal to 10 cm. When a current I passes through the coil of the solenoid, the magnetic field at the center of the solenoid has a magnitude B = 2 ?T. What is the largest value of the magnetic field in the solenoid for the same value of the current?
a)0.5 ?T
b)2.8 ?T
c)2.2 ?T
d)3.5 ?T
e)1.8 ?T