An apparatus and method for performing successive chemical or biochemical operations in an automated or semi-automated format are disclosed. The apparatus includes (i) a substrate having two or more wells, where each well is separated from adjacent well(s) by an energy barrier, (ii), a magnetic bead having a surface on which at least one of said operations is performed, and (iii) electromagnets positioned adjacent said wells, for use in producing controlled-time electromagnetic fields in one or more selected wells. A control unit operatively coupled to the electromagnets functions to produce controlled-time electromagnetic forces on the bead that are effective to transfer the bead from one well to another across the energy barrier and optionally, to agitate the bead within a well.