Two point charges `q` each placed at a distance `R` from each other in vacuum. The force between is `F_(1)` one of the charges is spread uniformly over the surface of a hemispherical bowl of radius R, while the other is spread uniformly over the volume of a sphere `r(rlt(R)/(2))` and both have a common centre O. the force on the sphere is `(F_(1))/(n)`. then n is

Answer

2

Explanation

`F_(1)=(Kq^(2))/(R^(2))`
Field due to shell at centre
`=(sigma)/(4epsi_(0))`
force `(sigma)/(4epsi_(0))xxq=(q)/(2piR^(2))xx(1)/(4epsi_(0))xxq`
`=(q^(2))/(4piepsi_(0)R^(2))xx(1)/(2)=(F_(1))/(2)`