The momentum of light in a refracting medium. II. Generalization. Application to oblique reflexion

Abstract

The expression for the momentum of a light wave in a refractive medium previously derived for the case of a sufficiently wide and short light pulse, is shown to be valid for a pulse of any shape, as long as its linear dimensions are large compared to the wavelength, and dispersion may be neglected. The 'prompt’ momentum transfer to a mirror immersed in a refractive fluid by the reflexion of a light pulse incident obliquely, with the electric vector in the plane of incidence, (4.7), is shown to differ appreciably from that which would follow from Minkowski’s theory. The momentum deposited in the medium is also determined, and its subsequent fate discussed. If the mirror is large enough, it also receives an amount of momentum equal to the ‘deposited’ momentum, and then the total received by the mirror equals the momentum change of the light.