A 4.0-cm-high object is placed at a distance of 60 cm from a concave lens of focal length 20 cm. Find the size of the image.

A point object O is placed at a distance of 20 cm from a convex lens of focal length 10 cm as shown in figure. At what distance x from the lens should a concave mirror of focal length 60 cm, placed so that final image coincides with the object ?

A point object is placed at a diatance of 25 cm from a convex lens of focal length 20 cm. If a glass slab of thickness t and refractive index 1.5 is inserted between the lens and the object, the image is formed at infinity. The thickness t is

A point object is placed at distance of 20 cm from a thin plane - convex lens of focal length 15 cm . The plane surface of the lens is now silvered . The image created by the system is :-

An object is placed at a distance of 25 cm on the axis of a concave mirror, having focal length 20 cm. Find the lateral magnification of an image.

A diverging lens with magnitude of focal length 25 cm is placed at a distance of 15 cm from a converging lens of magnitude of focal length 20 cm. A beam of parallel light falls on the diverging lens. The final image formed is ......

A point source S is placed at distance of 15 cm from a converging lens of focal length 10 cm . Where should a (i) concave mirror (ii) convex mirror of focal length 12 cm be placed so that real image is formed on object itself.

A point object is placed on the axis in front of a convex lens of focal length 30 cm. The distance of the object from the lens is 45 cm. If the lens is moved away from object by 1 mm and also the object is moved apart from the line joining the object and optical centre by 1 mm the displacement of the image has magnitude-

An object is kept at a distance of 16 cm from a thin lens and the image formed is real. If the object is kept at a distance of 6 cm from the same lens, the image formed is virtual. If the size of the image formed are equal, the focal length of the lens will be

An object is placed at a distance 40 cm in front of concave mirror. Focal length of mirror is 20 cm, so what will be type of image ?