Physics - Geometrical Optics Question with Solution | TestHub

There are two thin symmetrical lenses, one is converging, with refractive index ${\mathrm{n}}_1=1.70$, and the other is diverging with refractive index ${\mathrm{n}}_2=1.50$. Both lenses have the same curvature radius of their surface equal to $\mathrm{R}=10\mathrm{cm}$. The lenses are put close together and submerged into water. The focal length of lens system is found to be $\frac{100}{\mathrm{x}}\mathrm{cm}$ in water. What is the value of x. (R.I. of water $=4/3$ )