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

Answer

A

Explanation

We can see that system is equivalent to two electric dipoles of dipole moment p= qa along x- and y-axes, respectively. The resultant dipole moment is along their bisector and that is equal to qa`sqrt2`. We can see that the resultant dipole moment is along the line joining the points (0, 0, 0) and point (a, a, 0) as shown in the figure.