Two identical non-conducting solid spheres of same mass and charge are suspended in air from a common point by two non-conducting, massless strings of same length. At equilibrium, the angle between the strings is $\alpha$. The spheres are now immersed in a dielectric liquid of density $800 \mathrm{~kg} \mathrm{~m}^{-3}$ and dielectric constant 21. If the angle between the strings remains the same after the immersion, then