A concave mirror has radius of curvature of 40 cm. It is at the bottom of a glass that has water filled up to 5 cm (see figure). If a small particle…

A concave mirror has radius of curvature of $\displaystyle 40$ cm. It is at the bottom of a glass that has water filled up to $\displaystyle 5$ cm (see figure). If a small particle is floating on the surface of water, its image as seen, from directly above the glass, is at a distance $\displaystyle d$ from the surface of water. The value of d is close to : (Refractive index of water $\displaystyle =1.33$ )