One side of an equilateral prism is painted by a transparent material of refractive index \( n_{2} \). The refractive index of prism is \( 1.6 \). The minimum value of \( n_{2} \) required for total internal reflection from painted face is ______.
\( \dfrac{3\sqrt{3}}{1.6} \)
\( \sqrt{3} \)
\( \dfrac{3.2}{\sqrt{3}} \)
\( \dfrac{4\sqrt{3}}{5} \)