Question

y = 0 in second line.​

Answer 1

The given charge assembly can be represented using the three co-ordinate axes x, y and z as shown in figure.

The charge -2q is placed at the origin O. One + q charge is place at (a,0, 0) and the other +q charge is placed at(0, a, 0). Thus the system has two dipoles along x-axis and y-axis respectively.

As the electric dipole moment is directed from the negative to the positive charge hence the resultant dipole moment will be along OA where co-ordinates of point A are (a, a, 0). The magnitude of each dipole moment,

, p=qa

So, the magnitude of resultant dipole moment is

P

R

=

p

2

+P

2

=

(qa)

2

+(qa)

2

=

2

qa