In the Universal Gravitational Constant Experiment, students measure the attractive force between 2 sets of lead spheres. Using this force, the mass of each sphere, and the separation of the spheres, the universal gravitational constant can be determined.
The attraction between a pair of small lead spheres and a pair of larger lead 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, thus the laser reflection on the screen or wall is displaced. The displacement of the laser reflection is measured and an "optical lever" calculation is used to find "G".
PASCO Advantage:
PASCO's Gravitational Torsion Balance features a rugged torsion band that rarely needs to be replaced. If the band fails, it can be replaced using a screwdriver in less than 10 minutes. In addition, a "U"-shaped groove in the housing allows students to damp the oscillation of the small lead balls, reducing measurement time from hours to minutes. Finally, an equilibrium adjustment knob on the top of the unit allows the angle of the mirror to be easily adjusted.
Includes
- AP-8215A Gravitational Torsion Balance
- OS-8526A X-Y Adjustable Diode Laser -- Basic Optics
- ME-8736 45 cm Stainless Steel Rod
- ME-9472 Large Table Clamp
- Universal Gravitational Constant Experiment Manual
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