A convex lens is in contact with a concave lens. The magnitude of the ration of their focal lengths is `2//3`. Their equivalent focal length is 30cm. What are their individual focal lengths?

A convex lens if in contact with concave lens. The magnitude of the ratio of their focal length is (2)/(3) . Their equivalent focal length is 30 cm. What are their individual focal lengths?

A convex lens is in contact with a concave lens. The magnitude of the ratio of their powers is (3)/(2) . Their equivalent focal length is 30 cm. What are their individual focal lengths?

A convex lens of focal length 'f' is placed in contact with a concave lens of the same focal length. The equivalent focal length of the combination is

A thin convex lens of focal length 10 cm is placed in contact with a concave lens of same material and of same focal length. The focal length of combination will be

When a thin convex lens is put in contact with a thin concave lens of the same focal length (f), then the resultant combination has focal length equal to

A convex lens of focal length f_(1) is kept in contact with a concave lens of focal length f_(2) . Find the focal length of the combination.

A convex lens of power +2.5 D is in contact with a concave lens of focal length 25 cm. The power of combination is

A convex lens of focal length 10 cm is in contact with a concave lens. The focal length of the combination is numerically equal to that of the concave lens. The focal length of the concave lens is