An object is placed 60 cm from a concave lens. The image is formed at a distance of 20 cm from the optical centre. Find the focal length of the lens? Is the lens converging or diverging?

A doctor has prescribed a corrective lens of power+ 1.5 D.Find the focal length of lens.Is prescribed lens diverging or converging?

Draw a ray diagram to show how the image is formed when the object is placed between f and 2 f distances from a convex lens.Deduce the relation between the distances of he oject and the image from the lens and the focal length of the lens under this condition.

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

A double convex lens has 10 cm and 15 cm as its two radii of curvature.The image of an object,placed 30 cm from the lens,is formed at 20 cm from the lens on the other side.Find the refractive index of the material of the lens.Whgat will be the focal length ?What will be the focal length of the lens,if it is immersed in water of refractive index 1.33?

An object of 3 cm height is placed at a distance of 60 cm from a convex mirror of focal length 30 cm.Find the position and size of the image formed.

The graph between object distance u and image distance v for a lens is given below. The focal length of the lens is. .