A concave lens (refractive index =1 5 ) has both surfaces of same radius of curvature R . If it is immersed in a liquid of refractive index 1 75 it will act as a

Step-by-step solution

The behavior of a biconcave lens immersed in a liquid depends on the relative refractive indices. Given the lens material index n_L = 1.5 and the liquid medium index n_M = 1.75 , the lens maker's formula yields the focal length. For a biconcave lens with equal radii of curvature R , the radii are R₁ = -R and R₂ = +R by standard sign convention. Substituting into the formula: 1 f = ( n_L n_M - 1 ) ( 1 R₁ - 1 R₂ ) = ( 1.5 1.75 - 1 ) ( 1 -R - 1 R ) The refractive index term simplifies as 1.5 1.75 - 1 = - 1 7 , and the