Gravitational Torsion Balance and He–Ne–Laser

Gravitational Torsion Balance and He–Ne–Laser demonstrates gravitational attraction between two bodies and determines the gravitational constant.

For demonstrating gravitational attraction between two bodies and determining the gravitational constant. Highly sensitive torsion dynamometer, whose deflection can be observed and measured via a laser pointer. The torsion system consists of a bronze torsion band and a dumbbell-shaped torsion body with small lead balls and a mirror; the system is accommodated in a housing with front and rear windows, in order to shield it from interference by air currents. The housing is mounted on a stand rod, with a swiveling holder for large lead balls which are used to influence the torsion system. When the balls are displaced, the system starts oscillating slowly about its axis of rotation. Conclusions regarding the effective force between the large and small balls can be drawn from the pattern of the oscillations as well as the new state of equilibrium after the oscillations have died out