In the neutral point topic , what is the orientation of the magnet?
The orientation of the magnet here with respect to earth's magnetic field is the magnet is perpendicular to the earth's magnetic field.
14)Copper wire is not used in potentiometer. why?
Copper wire is not used in potentiometer because of its low resistivity. As a result resistance of the wire will be small and it will difficult to get a null point during the experiment.