In may experimental set-ups the source and screen are fixed at a distance say `D` and the lens is movable. Show that there are two positions for the lens for which an image is formed on the screen. Find the distance between these points and the ratio of the image sizes for these two points.

In many experimental set-ups, the source and screen are fixed at a distance say D and the lens is movable. Show that there are two positions for the lens for which an image is formed on the screen. Find the distance between these pionts and the ratio of the image sizes for these two points.

A lighted candle and the screen are placed at a fixed distance D apart. Show that the ratio of the two image sizes for two positions of the lens is ((D-d)/(D + d))^(2) ,where d is the distance between the two positions of the candle.

If the distance D between an object and screen than 4 times the focal length of a convex lens, then there are two positions of the lens for which image are formed on the screen. This method is called conjugate method. If d is the distance between the two positions of the lens, obtain the equation for focal length of the convex lens.

The size of the image formed ________ as the distance between the object and the lens decreases in convex lens.

A thin converging lens is placed between an object and a screen whose position are fixed. There are two positions of the lens at which the sharp image of the object is formed on the screen. Find the transverse dimension of the object if at one position of the lens the image dimension equal h' = 2.0 mm and at the other, h'' = 4.5 mm .

A thin convergent lens is placed between an object and a screen whose positions are fixed. There are two positions of a lens at which sharp image of the object is formed on the screen. If the size of the images in the two cases are 2 mm and 4.5 mm then the size of the object should be:-