1. The problem statement, all variables and given/known data A copper bar is moved to the right while its axis is maintained in a direction perpendicular to a magnetic field as shown in Figure P31.28d (image d, bottom right). If the top of the bar becomes positive relative to the bottom, what is the direction of the magnetic field? http://img370.imageshack.us/img370/5013/p3126jg2.th.gif [Broken] By lenz's law if the induced current should be opposing the change in magnetic flux. So if the magnetic flux is decreasing the induced current should be in such a way that the induced magnetic field is in the same direction as the magnetic field. And if the flux is increasing the induced magnetic field should be opposite the magnetic field. So in this problem I can't figure out how we are supposed to know whether the magnetic flux is increasing or decreasing. Not only that I thought that since the magnetic fields should oppose or contribute with each other then since the bar magnet has a magnetic field downward the answer would be either downward or upward. But neither of those is right. Any help please?