A flat coil of wire has an area A, N turns, and a resistance R. It is situated in a magnetic field, such that the normal to the coil is parallel to the magnetic field. The coil is then rotated through an angle of 90?, so that the normal becomes perpendicular to the magnetic field. The coil has an area of 1.5 × 10-3 m2, 50 turns, and a resistance of 170 ?. During the time while it is rotating, a charge of 8.1 × 10-5 C flows in the coil. What is the magnitude of the magnetic field?