Three point charges +q, –2q and +q are placed at points (x = 0, y = a, z = 0), (x = 0,y = 0, z = 0) and (x = a, y = 0, z = 0) respectively. The magnitude and direction of the electric dipole moment vector of this charge assembly are:-

Options

A. `sqrt2 qa` along + y direction
B. `sqrt2qa` along the line joining points `(x=0, y=0, z=0) and (x=a, y=a, z=0)`
C. qa along the line joining points `(x=0, y=0, z=0) and (x=a, y=a, z=0)`
D. `sqrt2 qq` along + x direction

Answer

B

Explanation

`p_("net") = sqrt(p^2+p^2)`
`=sqrt2p`
`= sqrt2qa`

Direction along OB
i.e. the line joining point (0,0,0) and (a,a,0).