LED, 5 mm, 20 mA, red

Allows the students observation of velocity of drop rising in an electric field, then permits calculation of the force on the charge carried by the oil drop.

Allows students to conduct experiments to measure the speed of light. Reflect a laser off a movable mirror into a light receiver to measure phase differences.

Replacement Spheres and collars for the Gravitational Torsion Balance (AP-8215A). Designed to convert to Tungsten while maintaining the proper large sphere dimensions.

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.