  In this note we show how to construct a number of nonconvex quadratic
inequalities for a variety of physics equations appearing in physical design
problems. These nonconvex quadratic inequalities can then be used to construct
bounds on physical design problems where the objective is a quadratic or a
ratio of quadratics. We show that the quadratic inequalities and the original
physics equations are equivalent under a technical condition that holds in many
practical cases which is easy to computationally (and, in some cases, manually)
verify.
