Two charges of each magnitude 0 . 01C and separated by a distance...

The formula to calculate the dipole moment is given by

$\left|\overset{⇀}{p}\right| = q\left|\overset{⇀}{d}\right| . . . \left(1\right)$

Substitute the values of the known parameters into equation (1) to calculate the dipole moment.

$\begin{cases}\left|\overset{⇀}{p}\right| & = & 0 . 01C \times 0 . 4mm \times \dfrac{1m}{{10}^{3}mm} \\ & = & 4 . 0 \times {10}^{- 6}C \cdot m\end{cases}$

The formula to calculate the torque on the dipole in the electric field is given by

$| \overset{\to}{τ} | = | \overset{\to}{p} \times \overset{\to}{E} | . . . \left(2\right)$

Substitute the values of the known parameters into equation (2) to calculate the required torque.

$\begin{cases}\left|\overset{⇀}{τ}\right| & = & 4 . 0 \times {10}^{- 6}C \cdot m \times 10dyne \cdot {C}^{- 1} \times \dfrac{1N}{{10}^{5}dyne} \times \sin 30 ° \\ & = & 2 \times {10}^{- 10}Nm\end{cases}$