An electric dipole has a fixed dipole moment $\overrightarrow{p}$, which makes angle $\theta$ with respect to x-axis. When subjected to an electric field $\overrightarrow{E_1} = E \hat{i}$, it experiences a torque $\overrightarrow{T_1} = \tau \hat{k}$. When subjected to another electric field $\overrightarrow{E_2} = \sqrt{3} E_1 \hat{j}$ it experiences a torque $\overrightarrow{T_2} = - \overrightarrow{T_1}$. The angle $\theta$ is :
