The power of a equi-concave lens is -4.5 D and is made of a material of refractive index 1.6, the radii of curvature of the lens is

Step-by-step solution

Power of equi-concave lens, P=-4.5 D Refractive index, =1.6 Focal length of lens, f= 1 P = ( 1 -4.5 ) m = ( 100 -4.5 ) cm = ( -200 9 ) cm By lens Maker's formula, we get 1 f =( -1) ( 1 R₁ - 1 R₂ ) For equi-concave lens, R₁=-R and R₂=R Putting these values in Eq. (i), we get aligned & 1 200 / 9 =(1.6-1) ( 1 -R - 1 R ) 9 200 =0.6 ( -2 R ) & R= -0.6 2 200 9 =-26.6 ~cm aligned