Fick's first law states that this value for a given quantity is equal on net to minus the diffusion constant times the gradient of that quantity.
A quantity of this name for neutrons is multiplied by the macroscopic fission cross-section to give the fission reaction rate in a nuclear reactor. In a type-II superconductor, the usual version of this quantity is quantized for the H field when the applied field is between two critical values; the inverse of that quantum is the Josephson constant. For electromagnetic energy, this quantity is represented by the Poynting vector. Fick's first law states that this value for a given quantity is equal on net to minus the diffusion constant times the gradient of that quantity. For the electric field, this quantity through a closed surface is proportional to the enclosed charge according to Gauss's Law. For 10 points, name this quantity, equal to the rate at which some physical quantity passes through a location per unit area.
A quantity of this name for neutrons is multiplied by the macroscopic fission cross-section to give the fission reaction rate in a nuclear reactor.
{flux} [accept {more specific} answers {such} as {neutron flux}, {electric flux}, {magnetic flux}, etc.]