An illuminated object and a screen are placed `90 cm` apart. What is the focal length and nature of the lens required to produce a clear image on the screen twice the size of the object ?

An iluminated object and a screen are placed 90 cm apart.Determine the focal length and nature of the lens required to produce a clear image on the screen,twice the size of the object.

A luminous object and a screen are at a fixed distance D apart. A converging lens of focal length f is placed between the object and screen. A real image of the object in formed on the screen for two lens positins if they are separated by a distance d equal to

A luminous object and a screen are at a fixed distance D apart. A converging lens of focal length f is placed between the object and screen. A real image of the object in formed on the screen for two lens positins if they are separated by a distance d equal to

An object and a screen are placed 80 cm apart. There are two positions at which a convex lens forms a real image on the screen, the magnification in the cases being 3/2 and 2/3. Calculate the focal length of the lens.

Aluminous object and a screen are placed on an optical bench and a converging lens is placed between them to throw a sharp image of the object on the screen, the linear magnification of the image is found to be 2.5. The lens is now moved 30 cm nearer the screen and a sharp image is again formed. Calculate the focal length of the lens.

A luminous object is separated from a screen by a distance D. What is the greatest focal length that a lens should have to focus the image of the object on the screen?

The distance between an object and a screen is 3 metre. What is the power of a lens which can produce an image twice the size of the object when placed in between the lens and the screen.

The image of an object placed at 60 cm in front of a lens is obtained on a screen at a distance of 120 cm from it. Find the focal length of the lens. What would be the height of the image of the object is 5cm high ?