Coulomb's Law Apparatus, Ontdek de wet van Coulomb. Accurately Measure Charge, Force and Distance Symmetric Design Minimizes Stray and Mirror Charges Magnetic Damping for Quick, Accurate Measurements With the ES-9070 Coulomb Law Apparatus, students can accurately measure charge, force and distance between two conductive spheres. Its symmetrical design minimizes stray and mirror charges and built-in magnetic damping ensures quick, accurate measurements.