1) A 0.84 kg copper rod rests on two horizontal rails 0.56 m apart and carries a current of 65 A from one rail to the other. The coefficient of static friction between rod and rails is 0.49. What is the magnitude of the smallest magnetic field that puts the rod on the verge of sliding?What is its angle (relative to the vertical)?
2) A long, rigid conductor, lying along an x axis, carries a current of 7.0 A in the negative x direction. A magnetic field B is present, given by B= 4.0i + 6.0x2 j, with x in meters andB in milliteslas. Calculate the k-component of the force on the 2 m segment of the conductor that lies between x = 1.0 m and x = 3.0 m.
3) 30-turn coil of wire of dimensions 8 cm by 5 cm. It carries a current of 0.140 A and is hinged along one long side. It is mounted in the xy plane, at an angle of 30° to the direction of a uniform magnetic field of magnitude 0.80 T. What is the torque acting on the coil about the hinge line.