A magician during a show makes a glass lens with n = 1.47 disappear in a trough of liquid. What is the refractive index of the liquid? Could the liquid be water?

Explanation

The refractive index of the liquid must be equal to 1.47 in order to make the lens disappear. This means` n_(1) = n_(2)` . This gives `1//f =0 or f rarr oo`. The lens in the liquid will act like a plane sheet of glass. No, the liquid is not water. It could be glycerine.