On the axis and on the equator of an electric dipole for all points . . . . . . .

The force on a charge situated on the axis of a dipole is $F$. If the charge is shifted to double the distance,the new force will be

An electric dipole with dipole moment $\vec{p} = \frac{p_0}{\sqrt{2}}(\hat{i}+\hat{j})$ is held fixed at the origin $O$ in the presence of a uniform electric field $\vec{E} = E_0 \hat{i}$. If the potential is constant on a circle of radius $R$ centered at the origin as shown in the figure,then the correct statement$(s)$ is/are:
($\varepsilon_0$ is the permittivity of free space,$R \gg$ dipole size)
$(1)$ $R = \left(\frac{p_0}{4 \pi \varepsilon_0 E_0}\right)^{1/3}$
$(2)$ The magnitude of the total electric field on any two points of the circle will be the same.
$(3)$ The total electric field at point $A$ is $\vec{E}_A = \sqrt{2} E_0(\hat{i}+\hat{j})$
$(4)$ The total electric field at point $B$ is $\vec{E}_B = 0$

Two charges each of magnitude $0.01\,C$ and separated by a distance of $0.4\,mm$ constitute an electric dipole. If the dipole is placed in a uniform electric field $\vec{E}$ of $10\,dyne/C$ making a $30^{\circ}$ angle with $\vec{E}$,the magnitude of torque acting on the dipole is:

Write the expression for the torque experienced by an electric dipole placed in a uniform electric field.

Two charges $+q$ and $-q$ are placed at a distance $a$ in a uniform electric field. The dipole moment of the combination is $2qa(\cos \theta \hat{i} + \sin \theta \hat{j})$, where $\theta$ is the angle between the direction of the field and the line joining the two charges. Which of the following statement$(s)$ is/are correct?