THE MAGNETIC-MOMENT QUADRIC AND CONDITIONS OF VANISHING MAGNETIC MOMENT FOR A ROTATIONAL CHARGED BODY

T which is different from the existent electric multiple-moment, and the concept of principal axes and principal-axis scalar charge moment, the condition of zero magnetic moment for an arbitrary rotational body with given charge distribution has been given explicitly in this paper. We find the loss of positive definiteness of T is its most important characteristic which forms a sharp contrast with that of its mechanic counterpart — the positive definite inertia tensor of rigid bodies. Meanwhile the relationship between the quadric distributive law of magnetic moment and the parameters of tensor T is discussed in detail. Accordingto the theory of analytic geometry, we give a series of test formulae, classify and enumerate every kind of possible quadric in a table. Finally, conclusion is given that any rotation axis which passes through origin O and alongwith any of the asymptotic line of the quadric (hyperboloids or hyperbolic cylinders) can lead to a vanishingmagnetic moment.