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 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

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) 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