THIN LENSES

Two thin convex lenses of focal lengths f_(1) and f_(2) are in contact and coaxial. The power of the combination is

Two coaxial thin lenses are placed in contact with each other and a small object is placed at a distance of 20cm from the combination of lenses. The focal length of each lens is 30 cm. What will be the distance between the object and the image when both the lenses are (i) convex (ii) concave

Two thin convex lenses of focal lengths 4 cm and 8 cm are separated by a distance of 4 cm in air. The combination will have the focal length

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

An astronomical telescope consists of the thin lenses, 36 cm apart and has a magnifying power 8 . Calculate the focal length of lenses. Two stars have an actual separation of one minute of arc. Find the angle of separation as seen through the telescope.

Four combinations of two thin lenses are given in List- I. The radius of curvature of all curved surfaces is r and the refractive index of all the lenses is 1.5. Match lens combinations in List-I with their focal length in List-II and select the correct answer using the code given below the lists.

A small object is placed at a distance of 15 cm from two coaxial thin lenses in contact. The focal length of each lens is 25 cm. what will be the distance between the object and its image when both the lenses are (i) convex, (ii) concave.