Question

Charges are placed on corners of square of side $a$ (as shown in figure). Find magnitude of net dipole moment.

• A. $qa$
• B. $\sqrt{2}qa$
• C. $\sqrt{3}qa$
• D. $2qa$

Answer 1

The correct option is B $\sqrt{2}qa$


The net dipole moment is a resultant of the three dipole moments as shown in the figure,
${\overrightarrow{p}}_{net}=(p_3-p_1)\hat{j}-p_2\hat{i}$
$=(2qa-qa)\hat{j}-qa\hat{i}$
${\overrightarrow{p}}_{net}=qa\hat{j}-qa\hat{i}$
$\Rightarrow |{\overrightarrow{p}}_{net}|=\sqrt{2}qa$