A black spot on the surface of a glass sphere of refractive index 3/2 is viewed from diametrically opposite positions.it appears to be a distance of 10 cm from the spot. Diameter of the sphere is
There is a black spot on a table. A glass slab of thickness 6 cm is placed on the table over the spot. Refractive index of glass is 3/2. At what depth from the upper surface will the spot appear when viewed from above?