Magnetic Monopoles and Duality.

We calculate the multipole moments in N = 2 and N = 4 super symmetric Yang-Mills theories and show that these are consistent with the duality symmetry between the vacuum and the monopole sector. Anomalous magnetic dipole moments of spin 1/2 and 1 charged particles and anomalous electric quadrupole moments of spin 1 charged particles vanish up to one loop only in the N = 4 theory. A magnetic monopole or a dyon with a spin carries an electric dipole moment due to the charge distribution arising from the fermionic zero mode and the corresponding deformation of the monopole. We show that the gyro-electric ratio from the electric dipole moment of the spin 1/2 and spin one monopole is two. In case of a dyon with a spin both gyromagnetic and gyroelectric ratios is two. Moreover we present the formulation that can be used to get radiative corrections systematically.