A convex lens is placed in contact with a plane mirror.A point object at a distance of 20 cm on the axis f this combinatin has its image coinciding with itself.What is the focal length of the lens?

A concave lens is placed in contact with a convvex lens of focal lenght 25 cm.the combinatin produces a real image at a distance of 80 cm,when the object is at a distance of 40 cm.What is the focal length of the concave lens?

A concave lens is placed in contact with a convex lens of focal length 25 cm.The combination produces a real image at adistance of 80 cm, when an object is at a distance of 40 cm. What is the focallength of concave lens ?

An object is placed at a distance of 1.5 m from a screen and a convex lens is interosed between them .the magnification produced is 4.What is the focal length of the lens?

A convex lens is 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?

An object is placed at a distance of f//2 from a convex lens .The image will be

A convex lens of focal lenght 20 cm is placed coaxially with a concave mirror of focal length 10 cm at a distance of 50 cm apart from each other.A beam of ligh coming parallel to the principal axis is incident on the convex lens.Find the position diagram showing the formation of the imge.

If the distance between the screen and object is 50 cm and the displacement of the lens is 10 cm,clculate the focal length of the lens.

A lens placed at a distance of 20 cm from an object produces a virtual image 2//3 the size of the object. Find the position of the image, kind of the lens and its focal length.