An electric dipole consists of two opposite charges of magnitude $q=1\times {10}^{-6 }\mathrm{C}$ separated by $2 \mathrm{cm}$. The dipole is placed in an external field of $1\times {10}^5$ $\mathrm{N} {\mathrm{C}}^{-1}$. What maximum torque does the field exert on the dipole? How much work must an external agent do to turn the dipole end for end, starting from position of alignment ($\text{θ}=0^0$)

The relation between the intensity of the electric field of an electric dipole at a distance r from its centre on its axis and the distance r is where ($r\gg 2l)$

Three charges of $+2q$, $-q$ and $-q$ are placed at the corners $A$, $B$ and $C$ of an equilateral triangle of side $a$, as shown in the adjoining figure. Then the dipole moment of this combination is