The adjoining figure represent a semi-circular loop of charge `Q` and of radius `R` .The minimum velocity with which a point mass `m`of charge `-q` should be projected so that it becoems free from the influence of the loop is

Options

A. `sqrt((2Qq)/(piepsilon_(0)mR))`
B. `sqrt((Qq)/(piepsilon_(0)mR))`
C. `sqrt((Qq)/(2piepsilon_(0)mR))`
D. `sqrt((Qq)/(4piepsilon_(0)mR))`

Answer

C

Explanation

`(1)/(2)mv^(2)-(1)/(4piepsilon_(0))(Qq)/(R)=0`
`v=sqrt((2Qq)/(4piepsilon_(0)mR))=sqrt((Qq)/(2piepsilon_(0)mR))`