A conducting rod with a length of 1.7 m is sliding along conducting rails, which are attached to a circuit. There is a uniform magnetic field pointing straight up, perpendicular to both the length of the rod and its velocity. The circuit has a resistance of 47 Ω. When the rod moves at a velocity of 6.8 m/s, an applied force of 1.55 N is required to keep it moving at constant velocity. What is the magnitude of the magnetic field?