Two point charges `+q` and `-q` are held fixed at `(-d,0) and (d,0)` respectively of a x-y coordinate system. Then,

Options

A. The electric field at all points on x-axis has the same direction
B. Electric field at all points on y-axis is along x-axis
C. Work has to be done in bringing a test charge from `oo` to the origin
D. The dipole moment is 2qd along negative x-axis

Answer

B, D

Explanation

E on x axis, E will not have same direction along entire x-axis
For `-dlexled`, the field is along `+x` - axis
For all other points, E is along negative x - axis
`E_(p)`, a point on y - axis is parallel to x - axis
Electric potential at origin = Zero
No work has to be done in bringing a test charge from `oo` to the origin
Dipole moment = 2qd along negative x - axis