Question

7. Charles Coulomb measured very small electrical forces with high precision using a torsion balance which

A. uses the Kelvin temperature scale, not Fahrenheit.

B. uses the rotation of the Earth, one revolution per day, to measure forces.

C. does the opposite of a regular balance.

D. twists a set amount for each Newton of force.

Answer 1

Solution

Answer: D. Twists a set amount for each Newton of force.

Coulumbs used the torsional balance setup. Which uses the restoring couple produced in a twisted wire. There will be charged balls(pitch balls) at the end of balance which is suspended at the middle by a wire. As another charged balls are brought near to these balls a force of attraction or repulsion due to electrostatic interaction between them occures which causes a tourque(couple) in the wire that twist the wire. Thus he measured the extent of twisting and thereby using couple per unit twist of wire he estimated the electrostatic force between the charges. The findings where in accordance with his inverse square law nature of force.