A current loop as a tiny magnet, and real magnets. Torque on a loop and magnetic moment, the moving-coil galvanometer and its conversion to an ammeter and a voltmeter, bar magnets, the Earth's field, and para-, dia- and ferromagnetism.
3 lessons, about 2 h 10 min5 simulations11 problems9 practice questionsPython in every lesson
Created by StemPy LabA current loop in a uniform magnetic field feels no net force, but it feels a torque, . The loop behaves as a magnetic dipole of moment , with and an energy . An orbiting electron is a tiny loop with .
A moving-coil galvanometer has a coil in a radial field, so the torque balances the spring at , and . A shunt in parallel makes an ammeter. A resistance in series makes a voltmeter. Meters change the circuit a little, and a good meter changes it least.
A bar magnet is a magnetic dipole of moment . Its field lines are closed loops, , and its field is on the axis and half of that on the equatorial line. The Earth's field has a dip and a horizontal part . Materials are diamagnetic, paramagnetic or ferromagnetic, as is small and negative, small and positive, or large and positive.
Log in to join the discussion.
Loading…