Immagini

DESCRIPTION

Exhibit 769 is a Cavendish balance designed by Henry Cavendish (1731-1810) to measure the gravitational constant. The device consists of two small metallic spheres each of mass m fixed to the ends of a lightweight bar suspended in horizontal position by a thin metal wire (see fig-1). There are two large spheres, each of mass M, placed near the small spheres. The entire complex is enclosed in a metal box. The force of attraction between the large spheres and the small spheres rotates the suspension wire to a new equilibrium position.

A beam of light coming from a source is reflected by a small mirror attached to the suspension wire and falls on a horizontal linear scale to be read by the method of Poggendorff (see exhibit 371). In this way the rotation angle is measured precisely.

See Youtube video of the experiment of Prof. Chiarotti Università di Roma Tor Vergata:

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