A thin convex lens made from crown glass has focal length

PHYSICS · Single correct · CBSE · Physics · Ray Optics and Optical Instruments · Ray Optics and Optical Instruments

Problem

A thin convex lens made from crown glass

\left(\mu = \frac{3}{2}\right)

has focal length

f

. When it is measured in two different liquids having refractive indices

\frac{4}{3}

and

\frac{5}{3}

, it has the focal lengths

f_1

and

f_2

respectively. The correct relation between the focal lengths is: (1)

f_1 = f_2 < f

(2)

f_1 > f

and

f_2

becomes negative (3)

f_2 > f

and

f_1

becomes negative (4)

f_1

and

f_2

both become negative