Question

Two point charges +q and -q are held fixed a (-d, 0) and (d, 0) respectively of a (X, Y) coordinate system. Then

• A. E at all points on the Y - axis is along $\hat{i}$
• B. The electric field $\dot{E}$ at all points on the X - axis has the same direction
• C. Dipole moment is 2qd directed along $\hat{i}$
• D. Work has to be done in bringing a test charge from infinity to the origin

Answer 1

The correct option is A E at all points on the Y - axis is along $\hat{i}$

From figure, it is clear that $\dot{E}$ at all points on the y-axis is along $\hat{i}$. Here $\dot{E}$ of all points on x-axis cannot have the same direction.
Here electric potential at origin is zero so no work is done in bringing a test charge from infinity to origin.

Here dipole moment is in - x direction (-q to +q)
Hence only option (a) is correct.