An equiconvex lens, with redii of curvature of magnitude `10 cm` each, is put over a liquid layer poured on top of a plane mirror. `A` small needle, with its tip on the principal axis of the lens, is moved along the axis until its inverted real image coincides with the needle itself. The distance of the needle, from the lens, is measured to be `15 cm` .
On removing the liquid layer, and repeating the experiment the distance is measured to be `10 cm` . Given that the two values of the distance measured represent the force length values in the two cases, calculate the refractive index of the liqiud.
