Teaching Minds-On Experiments on Electromagnetism in Secondary Schools

Lorentz force
One loop motor

Bend 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 movement.