Motional EMF is defined as E = -vBL Where B is the magnetic field in Tesla, L is the length in meters and ,v is the velocity. Lets say we have a distance(1m) where half of it(0.5m)the magnetic field is present. So, there is a wire that moves with constant acceleration throughout that whole distance. Is velocity equal to dx/dt? Where dx is the distance the field covers...? And dt is the time it takes for the wire to pass the field only correct? Does it make sense to say it's dx/dt with respect to the magnetic field? Change in the distance(in the magnetic field) and change in time(in the magnetic field) anything beyond the field does not matter or does not account to the velocity? Okay, what about using this formula: v = at , to calculate the velocity with respect to the time it takes for the wire to pass the field only not the whole path. Btw, when a wire moves in a constant uniform(or semi-uniform)magnetic field is that considered "change" in flux? Because -vBL = - dphi/dt? Edit: If the wire moved 0.5 meters in 100 milliseconds(before entering the field) the velocity is 0.5/0.100 = 5m/s... And then enters the field(0.5m wide) in another 100 milliseconds so the the velocity in motional emf is 0.5m/0.100 seconds or 1m/0.200 seconds?