Which Hungarian physicist invented the torsion pendulum used to measure gravity magnitude?

• A. Loránd Eötvös
• B. Albert Einstein
• C. Nikola Tesla
• D. James Clerk Maxwell

Answer: (A)

Using a torsion pendulum, tiny gravitational forces become a measurable twist of a suspended object. A slender fiber holds a bar with masses; gravity pulls on the masses, creating a torque that twists the fiber. The fiber’s restoring torque resists that twist, so the final angle of twist is proportional to the gravitational torque. By knowing the fiber’s torsional constant, you can deduce the strength of the gravitational interaction being measured. Loránd Eötvös, a Hungarian physicist, refined this method to compare how gravity acted on different materials and to test whether inertial and gravitational mass are the same. His precise torsion-balance experiments demonstrated the equivalence principle with high accuracy, and this apparatus became a classic tool for gravity studies. The other scientists listed are famous for other contributions, but they did not originate this gravity-measuring torsion balance, and they aren’t Hungarian.