👉 Waterhouse's theorem, also known as the water house theorem, is a fundamental result in mathematical physics that provides a precise relationship between the electric field and the current density of an infinite plane conductor when the field is applied parallel to the surface. It was first derived by John William Waterhouse in 1893 and has been widely used for studying the behavior of conductors under external magnetic fields. The theorem states that the magnitude of the electric field at a point on the conductor (which is