This thing has confused me for long .I have not come across any satisfactory answers on my own or while browsing through the internet. Everybody has seen the example of a rod moving while on parallel rails, with magnetic field perpendicular to the plane of loop formed by rod and rails. When the rod is an insulator, no current flows,direction of induced emf is easily understood. Now, consider the case in which rod is an conductor with some resistance . The induced emf across the rod according to faraday's law and voltage across it according to v = IR are in opposing directions. As,shown in the thumb nail ,if i attatch voltmeter across ab(Va-Vb) ends will it be positive ? if yes, then explain how drop caused by IR is not negative acrosss ab?