Two identieal metal spheres charged with +12 F and -8 F are kept at certain distance in air. They are brought into contact and then kept at the same distance. The ratio of the magnitudes of electrostatic forces between them before and after contact is

Step-by-step solution

aligned Q₁ &=12 F =12 10⁻⁶ ~F Q₂ &=-8 F &=-8 10⁻⁶ ~F aligned Initial value of electrostatic force of attraction between both spheres, aligned F₁ &= 1 4 ₀ Q₁ Q₂ r² &= 1 4 ₀ 12 10⁻⁶ 8 10⁻⁶ r² F₁ &= 1 4 ₀ 96 10⁻¹² r² aligned When both charged spheres are kept in contact, then new charges on the spheres will be aligned Q₁^ =Q₂^ &= Q₁+Q₂ 2 &= 12+(-8) 2 =2 F =2 10⁻⁶ ~F aligned Final value of electrostatic force between the spheres, aligned F₂ &= 1 4 ₀ Q₁^ Q₂^ r² &= 1 4 ₀ 2 10⁻⁶ 2 10⁻⁶ r² F₂ &= 1 4 ₀ 4 10⁻¹² r² aligned Fr