Question

A long thin walled pipe of radius R carries a current I along its length The current density is uniform over the circumference of the pipe . The magnetic field at the centre of the pipe due to quarter portion of the pipe shown , is A) μoI(2)1/2/42R B) μoI/2R C) 2μoI(2)1/2/2R D) none

Answer 1

I think it should be B option
as the magnitude of magnetic field at center of the coil is proportional to-
a}current
b}reciprocal of radius of the coil