Prototyp of an optical - electrical measuring system for the determination of the gravitational constant for teaching purposes

Newton’s gravitational constant plays an out-standing role in physics and is the most imprecisely determined natural constant from an experimental point of view. To determine this constant, one uses a set-up according to Cavendish, the so-called Cavendish experiment. The aim of the present work is to reconstruct this experiment and to implement a suitable measuring system with automated data acquisition and evaluation. This system is to be used in the physics lecture as a demonstrator and didactic support. Two tasks were addressed and solved:1.)mechanical construction of a torsion balance2.)automated measurement data acquisition and evaluation This paper deals with the second part. The result of this work is a complete characterization of the mechanical properties of the torsion balance and the construction of a functional, automated optical-electrical measuring and evaluation system for determining the gravitational constant $\gamma$.