Analysis of nonmetric theories of gravity. II. The weak equivalence principle

A set of equations representing the (generalized) laws of electromagnetism in a gravitational field for a class of nonmetric theories of gravity are written down. From these equations we calculate the center-of-mass acceleration $〈{\overrightarrow{\mathrm{A}}}_{\mathrm{c}.\mathrm{m}.\mathrm{}}〉$ of a composite test body, consisting of electromagnetically interacting charged point particles, in an external, spherically symmetric and static (SSS) gravitational field. Demanding that the weak equivalence principle be satisfied, so that $〈{\overrightarrow{\mathrm{A}}}_{\mathrm{c}.\mathrm{m}.\mathrm{}}〉$ contains no composition-dependent terms, puts severe constraints on the form of the original generalized equations. Indeed, the principle demands that the laws of electromagnetism in an (SSS) gravitational field take on a "metric" form. The observational constraints on the form of the (generalized) laws of electromagnetism from Eötvös experiments are also discussed.