Question

coulomb use which device for his experiment​

Answer 1

Tesla's Egg of Columbus was a device exhibited in the Westinghouse Electric display at the 1893 Chicago World's Columbian Exposition to explain the rotating magnetic field that drove the new alternating current induction motors designed by inventor Nikola Tesla by using that magnetic field to spin a copper egg on end

Answer 2

Answer:

with a metal-coated ball attached to one end, suspended by a silk thread.

Explanation:

In Coulomb's experiment, the torsion balance was an insulating rod with a metal-coated ball attached to one end, suspended by a silk thread. The ball was charged with a known charge of static electricity, and a second charged ball of the same polarity was brought near it.