A concave lens of glass, refractive index 1.5 has both surfaces of same radius of curvature R.On immersion ina medium of refractive index 1.75 it will behave asa lens

A concave lens of glass, refractive index 1.5 has both surfaces of sam

1.	A concave lens of glass, refractive index 1.5 has both surfaces of same radius of curvature R.On immersion ina medium of refractive index 1.75 it will behave asa lens
Answer» Solution :When glass LENS is immersed in a MEDIUM, its refractive index `^m mu_s. ^m mu_s= ^amu_G/mu_g = 1.50/1.75=6/7` `therefore` By lens MAKER formula `1/f=(m mu_g-1) (1/R_1-1/R_2) or 1/f=(6/7-1)(-1/R-1/R)` or `1/f=(-1/7) (-2/R) or f=(7R)/2=3.5 R` Hence the given lens in medium behaves like convergent lens of FOCAL length 3.5R.