A small ball of paper has mass `9xx10^(-5) kg` and carries a charge of `5muC`. When it is held over another charged ball of paper at a distance of 2cm above it, the two balls stay in equilibrium. What is the charge on the second hall ?

Answer

`7.84xx10^(-12)C`

Explanation

`q_(1) = 5 mu C = 5xx10^(-6) C, q_(2) = ?`
`r = 2cm = 2xx10^(-2) m`
`m= 9xx10^(-5) kg`.
`F = (q_(1) q_(2))/(4pi in_(0) r^(2)) = mg`
`(9xx10^(9)xx5xx10^(-6) q_(2))/((2xx10^(-2))^(2)) = 9xx10^(-5)xx9.8`
`q_(2) = 7.84xx10^(-12)C`