Q. A thin convex lens L(refractive index
=1.5) is placed on a plane mirror M. When a pin is placed at A, such that OA
=18cm, its real inverted image is formed at A itself, as shown in figure. When a liquid of refractive index
μ1 is put between the lens and the mirror. The pin has to be moved to A', such that
OA′=27cm, to get its inverted real image at A' itself. The value of
μ1 will be?