A liquid of refractive index 1.6 is contained in the cavity of a glass specimen of refractive index 1.5 as shown in figure. If each of the curve surface has a radius of curvature of 0.20m, the arrangement obehaves as a

Options

A. converging lens of focal length 0.25m
B. diverging lens of focal length 0.25m
C. diverging lens of focal length 0.17m
D. converging lens of focal length 0.72m

Answer

b.

Explanation

Power of liquid lens
`=(1.6-1)((2)/(0.20))=(6)/(10)xx10=6D`
Power of concave lens
`=-(1.5-1)=-0.5xx10D`
Total power of two concave lenses `=-10D`
Power of system
`=-10D+6D=-4D`
Focal length `=(1)/(-4)=-0.25m`