question_answer

In using Amperes law to find the magnetic field of a straight, long solenoid, the loop (Amperian loop) that is taken is

A)  a circular loop, coaxial with the solenoid

B)  a rectangular  loop  in   a  plane perpendicular to the axis of the solenoid

C)  a rectangular loop in a plane containing the axis of the solenoid, the loop being totally within the solenoid

D)  a rectangular loop in a plane containing the axis of the solenoid, the loop being partly inside the solenoid and partly outside it