When a test charge is brought in from infinity along the perpendicular bisector of an electric dipole,the work done is ..........

An electric dipole is placed at the origin in the direction of the $x$-axis. $A$ point $P$ is at a distance of $20 \, cm$ from the origin $O$ such that $OP$ makes an angle of $\pi/3$ with the $x$-axis. If the electric field at point $P$ makes an angle $\theta$ with the $x$-axis,then the value of $\theta$ is:

$A$ given charge situated at a distance $r$ from an electric dipole on its axis experiences a force $F$. If the distance of the charge from the dipole is doubled,the force acting on the charge will be

Write the equation for the electric field produced by an electric dipole at a point on its axial line,given the condition $r >> a$.

$A$ point particle of mass $M$ is attached to one end of a massless non-conducting rod of length $L$. Another point particle of the same mass is attached to the other end of the rod. The two particles carry charges $+q$ and $-q$ respectively. This arrangement is placed in a region of uniform electric field $E$. When the rod makes a small angle $(< 5^o)$ with the direction of the field,what is the minimum time required for the rod to become parallel to the field?

The electric potential at a point on the axis of an electric dipole depends on the distance $r$ of the point from the dipole as