Question

The drawing shows three identical rods (A, B, and C) moving in different planes. A constant magnetic field of magnitude 4.50 T is directed along the +y axis. The length of each rod is L = 1.3 m, and the speeds are the same, vA = vB = vC = 2.6 m/s. For each rod, find the magnitude of the motional emf, and indicate which end (1 or 2) of the rod is positive. rod A V ---Select--- End 1 is positive. End 2 is positive. No emf in rod. rod B V ---Select--- End 1 is positive. End 2 is positive. No emf in rod. rod C V ---Select--- End 1 is positive. End 2 is positive. No emf in rod.

Answer 1

A)

The emf is zero because the velocity of the rod is parallel to the direction of the magnetic field, so the charges experience no force.

B)

The emf is vBL

= (2.6 m/s)(4.50 T)(1.3 m)

= 15.21 V.

The positive end is end 2.

C)

The emf is zero because the magnetic force on each charge is directed perpendicular to the length of the rod.