Question

A water current in the ocean flows with a velocity ? ⃗ in the presence of a magnetic field ? :⊥?. The fluid has an electrical conductivity s and a volumetric mass density p.

a. Evaluate the current density ? ⃗ that is induced in the fluid.

b. Estimate the magnitude of ? ⃗ for terrestrial ocean currents for the parameters of the Earth’s magnetic field ~ 5x105 T, conductivity of sea water ~4 W-1m-1, and typical ocean current velocity 1 m/s.

c. The magnetic field acts upon the induced current to retard the water current. Estimate the damping time of this effect

Answer 1