Let us assume that charges on Earth and Sum are not neutralised and net charges are of equal magnitude and similar nature. What must be the charge on each so that coulomb force just cancels gravitational force ? This charge corresponds to how many free electrons ?
Mass of sun `= 2xx10^(30) kg`
Mass of earth `= 6xx10^(24) kg`

Answer

`29.8xx10^(16)C ; 1.86xx10^(36)`

Explanation

Here, electrostatic force of repulsion must be equal to gravitational force.
`F_(e) = F_(g)`
`(9xx10^(9)xx Q^(2))/(r^(2)) = (GMm)/(r^(2))`
`9xx10^(9)xx Q^(2) = 6.67xx10^(-11)xx2xx10^(30)xx6xx10^(24)`
`Q = 29.8xx10^(16)C`
As `Q =n e`
`n = 1.86xx10^(36)`