Question

Two small identical electrical dipoles AB and CD each of dipole moment p are kept at an angle of ${120}^0$ as shown in the figure. If this system is subjected to electric field (E) directed along -x direction. Then, the magnitude and direction of the torque acting on this is

• A. $\frac{\sqrt{3}}{2}pE$, along - Z-axis
• B. $\frac{1}{2}pE$, along - Z-axis
• C. $\frac{\sqrt{3}}{2}pE$, along Z-axis
• D. $\frac{1}{2}pE$, along Z-axis

Answer 1

The correct option is C $\frac{\sqrt{3}}{2}pE$, along Z-axis

$\begin{array}{c}MAB:\tau =\overrightarrow{P}\times \overrightarrow{E}\\ =PE\\ MBC:PE\sin {30}^0\\ \frac{PE}{2}\\ \therefore Net\tau =\frac{PE}{2}alongz-axis\\ Hence,\\ optionCiscorrectanswer.\end{array}$