Universal Gravitational Constant

A Cavendish Balance is used to determine the Universal Gravitational Constant, G. The attraction between a pair of small tungsten spheres and a pair of larger tungsten spheres is measured by the torsion of a beryllium ribbon. The large spheres are placed close to the small spheres and allowed to equilibrate. A laser is reflected from a mirror on the beryllium ribbon and shown on a screen or wall.

The large spheres are then rotated through an angle to produce torque on the ribbon. The mirror rotates with the ribbon, so the laser reflection on the screen or wall is displaced. The displacement of the laser reflection is measured to find “G”.

Grade Level: College

Subject: Physics

Student Files

	EX-5550 Cavendish	33.46 MB
	Universal Gravitational Constant	1.47 MB

Teacher Files

Featured Equipment

Universal Gravitational Constant Experiment

Recreate Cavendish’s historical experiment and measure the Universal Gravitational Constant in under three hours with this complete solution designed for use with PASCO Capstone Software.

Gravitational Torsion Balance

Combines features that significantly improve the ease of setup, the durability of the Torsion Band and the quality of results. In the newer models the spheres are tungsten rather than lead.

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Source Collection: Lab #19