k times the kth multipole moment.
This quantity as a function of r is proportional to the sum over all k of the Legendre polynomial of r of order k times the kth multipole moment. One of these equal to minus current times magnetic field over the product of plate depth, fundamental charge, and carrier density develops in the presence of a perpendicular B field. The Laplacian of this quantity is set proportional to charge in Poisson's equation, and capacitance is proportional to one over the change in this quantity across a component. For 10 points, name this quantity, whose drop across an electrical component is called voltage and whose negative gradient gives the electric field.
This quantity as a function of r is proportional to the sum over all k of the Legendre polynomial of r of order
electric scalar {potential} [or {emf}; or electromotive {force}]