Stewart, Andrew2015-12-130143-0807http://hdl.handle.net/1885/79833The angular momentum of a classical electromagnetic plane wave of arbitrary extent is predicted to be, on theoretical grounds, exactly zero. However, finite sections of circularly polarized plane waves are found experimentally to carry angular momentum, and it is known that the contribution to the angular momentum arises from the edges of the beam. A mathematical model is described that gives a quantitative account of this effect and resolves the paradox.Keywords: Electric field effects; Electromagnetic wave polarization; Electromagnetic wave propagation; Integration; Magnetic field effects; Mathematical models; Maxwell equations; Vectors; Angular momentum; Finite elements; Plane waves; Polarized plane; Electromagn Angular momentum; Boundaries; Helmholtz theorem; Light; Orbital; Plane waves; Spin200510.1088/0143-0807/26/4/0082015-12-11