Two thin sysmmetrical lenses of different nature and of different material have equal raii of curvature `R=15cm`. The lenses are put close together and immersed in water `(mu_(w)=4//3)` . The focal length of the system ini water is 30cm. The difference between refractive indices of tthe two lenses is

Two thin symmetrical lenses of different nature and of different material have equal radii of curvature R = 15 cm . The lenses are put close together and immersed in water (mu_(w) = (4)/(3)) . The focal length of the system in water is 30 cm. The difference between refractive indices of the two lenses is

Two identical glass (mu_(g)=3//2) equiconvex lenses of focal length f are kept ini contact. The space between the two lenses is filled with water (mu_(w)=4//3) . The focal length of the combination is

The radii of curvature of a lens are +20cm and +30cm .The material of the lens has a refractive index 1.6 .Then focal length of the lens (in cm) if it is placed in water of refractive index mu =(4)/(3) is

Two identical glass (mu_(g)=3//2) equiconvex lenses of focal length f are kept in contact. The space between the two lenses is filled with water (mu_(w)=4//3) . The focal length of the combination is

Two identical glass (mu_(g)=3//2) equi- convex lenses of focal length f each are kept in contact. The space between the two lenses aiisolfilled with water (mu_(g)=4//3). The focal length of the combination is

There are two thin symmetrical lenses : one is converging , with refractive index n_(1) = 1.70 , and the other is diverging with refractive index n_(2) = 1.51 . Both lenses have the same curavature close together and submerged into whater. What is the focal length of this system in water ?

The focal length of lens of refractive index 1.5 in air is 30cm When it is immersed in water of refractive index (4)/(3) ,then its focal length will be

Two identical equiconvex lenses of refractive index 3//2 and focal length 16 cm are kept in contact. The space between the lenses is filled with water of refractive index 4//3 . What is the focal length of the combination ?

Two thin converging lenses of focal length 15 cm and 30 cm are held in contact with each other. The focal length of the combination is