Three magnetic compasses are placed at the corners of a horizontal equilateral triangle. as in any ordinary compass, each compass
needle is a magnetic dipole constrained to rotate in a horizontal
plane. in this case the earth’s magnetic field has been precisely
annulled. the only field that acts on each dipole is that of the other
two dipoles. what orientation will they eventually assume? (use
symmetry arguments! ) can your answer be generalized for n compasses at the vertices of an n-gon?