When two spheres having 4Q and - 2Q charge are placed at a certain distance, the force acting between them is F. Now they are connected by a conducing wire and again separated from each other. Now they are kept at a distance half of the previous one. The force acting between them is.......

Options

A. F
B. `F/4`
C. `F/2`
D. `F/8`

Answer

C

Explanation

`F =k((4Q)(-2Q))/r^(2) =-(8kQ^(2))/r^(2)`
`F. = k((Q)(Q))/(r.)^(2) =(4kQ^(2))/r [therefore r.=r/2]`
`therefore F^(.)/F =(4kQ^(2))/r^(2) xx (-r^(2))/(8kQ^(2)) =-1/2`
`therefore F. = F/2, therefore |F.| = |F/2|`