Angular momentum transferred by the field of a moving point charge

The flux of angular momentum of the electromagnetic field of an arbitrarily moving point charge is investigated. General equations for the transfer of angular momentum at arbitrary distance from the charge are obtained, and corresponding equations in the far-field approximation are derived. An explicit expression is obtained for the flux of angular momentum in the wave zone in terms of coordinates, velocity, and acceleration of the charge. The torque that would act on an object if it absorbs the incident radiation is calculated. It is shown that this torque is proportional to the curl of the stress tensor of the electromagnetic field; in the far-field approximation the torque is proportional to the curl of the Poynting vector. Application of the obtained formulas is illustrated by the example of a rotating dipole.