Explore experiments

Mass spectrometer

Two ions carrying the same charge enter the same magnetic field at the same speed, and the field sorts them by mass. A magnetic force is always perpendicular to the motion, so it never speeds anything up -- it only bends. The heavier ion bends wider and lands further along the plate; the gap between the landing points is the measurement. Nothing is choreographed: the engine applies F = q(v x B) every step and the arcs are whatever that produces.