Teaching Minds-On Experiments on Electromagnetism in Secondary Schools 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.