Two small spheres, each having a mass of 20 g, are suspended form a common point by two insulating strings of length 40 cm each. The spheres are identically charged and the speration between the balls at equilibrium is found to be 4 cm . Find the charge on each sphere.

Explanation

`T=costheta=mg ………(i) `
` Tsintheta=F_e ………(ii) `
Using given conditions in above two equations, we get,
` rArr Q^2 = 17xx10^-7xx10^-9 `
` 17xx10^-16 `
` Q=sqrt(17xx10^-16 ) `
` =4.123xx10^-8C`