Current in a bottle ** An ocean current flows at a speed of 2 knots (approximately 1 m/s) in a region where the vertical component of the earth's magnetic field is 0.35 gauss. The conductivity of seawater in that region is 4 (ohm-m)−1. On the assumption that there is no other horizontal component of E than the motional term v×B, find the density J of the horizontal electric current. If you were to carry a bottle of seawater through the earth's field at this speed, would such a current be flowing in it?