Torsionsbalansen

Torsionsbalansen, often translated as torsion balance, is a scientific instrument used to measure very small forces or torques. Its fundamental principle relies on the elastic properties of a thin fiber or wire. When a force or torque is applied to an object suspended by this fiber, the fiber twists, or undergoes torsion. The amount of twist is directly proportional to the applied force or torque. By calibrating the instrument, this twist can be used to quantify the magnitude of the force or torque with high precision.

The most famous application of the torsion balance was by Henry Cavendish in 1797. He used a torsion balance to measure the gravitational attraction between two lead spheres. This experiment allowed him to determine the Earth's average density and, consequently, the gravitational constant G. The design typically involves a horizontal rod suspended by a thin fiber. Weights are attached to the ends of the rod, and their interaction with other masses placed nearby creates the force being measured. A mirror attached to the rod, often combined with a light beam and scale, amplifies the small angular deflection caused by the torsion, allowing for precise readings. Torsion balances are sensitive instruments, requiring careful isolation from vibrations and temperature fluctuations to achieve accurate measurements. Beyond gravitational experiments, they have been employed in various fields, including electromagnetism and the study of intermolecular forces.