The magnifications produced by a convex lens for two different positions of an object are `m_(1)` and `m_(2)` respectively `(m_(1) gt m_(2))`. If 'd' is the distance of separation between the two positions of the object then the focal length of the lens is

In the displacement method a conves lens is placed in between an object and a screen. If the magnificaiton in the two position are m_(1) and m_(2) ( m_(1) gt m_(2) ), and the distance between the two positions of the lens is x, the focal length of the lens is

The lateral magnification of the lens with an object located at two different position u_(1) and u_(2) are m_(1) and m_(2) , respectively. Then the focal length of the lens is

The lateral magnification of the lens with an object located at two different position u_(1) and u_(2) are m_(1) and m_(2) , respectively. Then the focal length of the lens is

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 magnifications for two positions of image of the same lens are 3 and 2, of a fix point object on a fix screen when the distance between the two positions of lens is 30 cm . The focal lengths of the lens is