A thin rod of length L is magnetized and has magnetic moment M . The rod is then bent in a semicircular arc. The magnetic moment in the new shape is

Step-by-step solution

Length of arc L = π R ⇒ R = L π               . . . 1 Magnetic moment of rod M = m L       . . . 2 Magnetic moment of semicircular arc M arc = m 2 R ⇒ M arc = m 2 L π ⇒ M arc = 2 π m L ⇒ M arc = 2 π M