Teaching Minds-On Experiments on Electromagnetism in Secondary Schools Lorentz force One loop motor
the wire as on the picture: a flat frame, with a pin at the top side
and a ring at the bottom. Stand the battery on top of the magnet and
rest the frame on it. The loop must lightly touch the magnet.
When the loop touches the magnet, the circuit is closed and a current
starts to run. Essentially, we have a moving charge in a magnetic
field. This provokes a Lorentz force on the charge, perpendicular on
its direction of movement and on the magnetic field. The current
through the magnet is roughly horizontal, the magnetic field is
vertical, so the force is sideways. The direction of the movement is
given by the ‘right-hand rule’: the index finger in the direction of
the current, the thumb to the north pole of the magnet, then the middle
finger of the half closed hand gives the direction of the force.
Inverting the magnet or the battery changes the direction of the