Two point charges +q and -q are placed at point A and B respectively which are at a distance 2m apart. C is the midpoint between A and B. The work done by external agent in moving a charge Q slowly along the triangular path CED
`(AC=BC=BD) `

Options

A. `2/5kQq`
B. `-2/3kQq`
C. `-(kQq)/(4)`
D. `(kQq)/(2)`

Answer

B

Explanation

`W=Delta U = q DeltaV`
`V_C=(kq)/(1)+(K(-q))/(1)= 0`
`V_D=(Kq)/(3) +(K(-q))/(1) = (-2Kq)/(3)`
`W=Q(V_D-V_C) =Q(-2/3 Kq - 0)`
`=-2/3KQq`