Two plano-concave lenses of glass of refractive index 1.5 have radii of curvature of 20 and 30 cm. They are placed in contact with curved surface towards each other and the space between them is filled with a liquid of refractive index `(4)/(3)`, find the focal length of the system.

Two plano-concave lenses of glass of refractive 1.5 have radii of curvature of 20 and 30 cm. They are placed in contact with curved surface towards each other and the space between yhem is filled with a liquid of refractive index 2/3. Find the focal length of the system.

Two plano concave lenses of glass of refractive index 1.5 have radii of currature 20cm and 30cm respectively.They are placed in contact with the curved surface to wards each other and the space between them is filled with a liquid of refractive index (5)/(2) . The focal length of the combination is (in cm)

Two plano concave lenses of glass of refractive index 1.5 have radii of currature 20cm and 30cm respectively. They are placed in contact with the curved surface to wards each other and the space between them is filled with a liquid of refractive index 3. The focal length of the combination is (in cm) (A) 12 (B) 16 (C) -92

Two plano-concave lenses (1 and 2) of glass of refractive index 1.5 have radii of curvature 25 cm and 20 cm. They are placed in contact with their curved surface towards each other and the space betweent hem is filled with liquid of refractive index (4)/(3) the the combination is

A plano convex lens is made of glass of refractive index 1.5. The radius of curvature of its convex surface is R. Its focal length is