In the given figure, the face $$AC$$ of the equilateral prism is immersed in a liquid of refractive index $$n$$. For incident angle $$60°$$ at the side $$AC$$, the refracted light beam just grazes along face $$AC$$. The refractive index of the liquid $$n = \dfrac{\sqrt{x}}{4}$$. The value of $$x$$ is ______. (Given refractive index of glass $$= 1.5$$)