# A biconcave lens made of a transparent material of refractive index 1.25 is immersed in water of refractive index 1.33. will the lens behave as a converging or diverging lens? give reason.

1
by LiguShenoy

2015-09-21T22:45:28+05:30

### This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
As lens is less optically dense than water,  it will behave as a converging lens.  It will change its behaviour from concave to convex.

if the ratio, of the refractive index of the lens and the medium around it , is more than 1 then the lens will behave as a concave lens.

if the ratio is less than 1, then the lens will behave as  a  convex lens.

the lens makers formula for the concave lens is given by :

1/f =  (n2 / n1 - 1) [- 2 / R ]

f = focal length,    n2 = refractive index of the medium of lens.
n1 = refractive index of medium around the lens
R = radius of curvature of the lens surfaces.

HERE, if  n2 > n1  ,  then  f = negative.  so  it is a concave lens.  The rays diverge from the lens.  This is  because the angle of incidence/refraction in the medium 1 is more than that of lens medium.  The rays bend towards normal in the lens.

if  n2 < n1 ,  then then the lens will act as a convex lens.  It is because, the rays bend away from the normal and converge towards the principal axis.

click on thanks button above please