question_answer 30)

  A current carrying circular loop of radius R is placed in the x-y plane with centre at the origin. Half of the loop with x > 0 is now bent so that it now lies in the y-z plane. (a) The magnitude of magnetic moment now diminishes (b) The magnetic moment does not change (c) The magnitude of  at (0,0,z), z >> R increases (d) The magnitude of  at (0,0,z), z >> R is unchanged

Answer:

                        (a)For a circular loop of radius R, carrying current in x-y plane, the magnetic moment M = . It acts perpendicular to the loop along z-direction. When half of the current loop is bent in y-z plane, then magnetic moment due to half current loop in x-y plane, acting along z-direction. Magnetic moment due to half current loop in y-z plane, along x-direction. Effective magnetic moment due to entire bent current loop, M' = i.e., magnetic moment diminishes. The magnitude of  at a point on the axis of loop, distance z from the centre of current loop in x-y plane is                             The magnitude of  at a point distance z from the centre of bent current loop, whose half part is in x-y plane and half part is in y-z plane, is