Eddy currents are electric currents that can arise in a piece of metal when it moves through a region where the magnetic field is not the same everywhere. the drawing shows, for example, a metal sheet moving to the right at a velocity and a magnetic field that is directed perpendicular to the sheet. at the instant represented, the field only extends over the left half of the sheet. an emf is induced that leads to the eddy current indicated. such eddy currents cause the velocity of the moving sheet to decrease and are used in various devices as a brake to damp out unwanted motion. does the eddy current in the drawing circulate (a) counterclockwise or (b) clockwise?