Fr.: vecteur de Poynting
The amount of electromagnetic energy flowing through unit area, perpendicular to the direction of energy propagation, per unit time, given by (c/2 π)[E x H]. → Poynting's theorem.
Fr.: théorème de Poynting
The space through which electromagnetic radiation passes is filled with electric and magnetic fields at right angles to each other and to the direction of propagation of the radiation. The rate of energy transfer is given by the Poynting vector.
In honor of John Henry Poynting (1852-1914), English physicist; → theorem.
Fr.: traînée de Poynting-Robertson
A loss of → orbital angular momentum by tiny ring particles associated with their absorption and re-emission of → solar radiation. Also known as the → Poynting-Robertson effect (Ellis et al., 2007, Planetary Ring Systems, Springer).
Fr.: effet Poynting-Robertson
The effect of → solar radiation on a small (centimeter-sized) particle in → orbit around the Sun that causes it to lose velocity and fall gradually into the Sun. The particle → absorbs solar radiation and → radiates the energy → isotropically in its own frame. The particle thereby preferentially radiates (and loses → angular momentum) in the forward direction in the → inertial frame of the Sun (aberration effect). This leads to a decrease in the particle's angular momentum and causes it to spiral sunward. In contrast, the → Yarkovsky effect is anisotropic; the object may be accelerated or decelerated.