A circularly polarized electromagnetic beam is considered, which is absorbed by a plane, and the mechanical stress produced in the plane by the beam is calculated. It is shown that the central part of the beam produces a torque at the central region of the plane due to the spin of the beam, and the wall of the beam produces an additional torque due to orbital angular momentum of the beam. The total torque acting on the plane equals two power of the beam divided by the frequency. This fact contradicts the standard electrodynamics, which predicts the torque equals power of the beam divided by frequency, and means the electrodynamics is incomplete. An introducing of the spin tensor corrects the electrodynamics.
Category: Classical Physics