Two small spheres each having equal positive charge $Q$ (Coulomb) on each are suspended by two insulating strings of equal length $L$ (metre) from a rigid hook (shown in figure). The whole set up is taken into satellite where there is no gravity. The two balls are now held by electrostatic forces in horizontal position, the tension in each string is then
In this case, tension will be equal to force The tension in each string $T =F $ $=\frac{1}{4 \pi \varepsilon_{0}} \frac{Q^{2}}{(2 L)^{2}} $ $=\frac{Q^{2}}{16 \pi \varepsilon_{0} L^{2}}$
In 1785, french physicist Charles Augustin de Coulomb coined a tangible relationship in mathematical form between two bodies that have been electrically charged. He represented an equation for the force causing the bodies to attract or repel each other which is commonly known as Coulomb’s law or Coulomb’s inverse-square law.
As per Coulomb’s law, the force of attraction or repulsion between two charged bodies is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. It acts along the line joining the two charges regarded to be point charges.
Coulomb’s Law has an abundant application to modern life, from Xerox machines to laser printers, to powder coating.
