When a biconvex lens of glass of refractive index 1.5 is dipped in a liquid, it acts like a plane sheet of paper. This means the refractive index of the liquid is

Step-by-step solution

The lens maker formula is given by 1 f = ( _ rel - 1) ( 1 R₁ - 1 R₂ ) , where _ rel = _ lens _ liquid . When the lens acts like a plane sheet of paper, its focal length f becomes infinite, which implies 1 f = 0 . Substituting this into the lens maker formula, we get ( _ rel - 1) = 0 , which means _ rel = 1 . Since _ rel = _ lens _ liquid , we have _ lens _ liquid = 1 , implying _ liquid = _ lens . Given the refractive index of the glass lens is 1.5, the refractive index of the liquid must be equal to 1.5, which is