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.

An object is kept at 10 cm in front of a convex lens. Its imge is formed on the screen at 15 cm from the lens. Calculate the focal length of the lens.

A screen is placed 80 cm from an object. The image of the object on the screen is formed by a convex lens at two different locations separated by 10 cm . Calculate the focal length of the lens used.

A source of light and a screen are placed 90 cm apart. Where should a convex lens of 20 cm focal length be placed in order to form a real image of the source on the screen ?

A screen is placed 90 cm from an object. The image of the object on the screen is formed by a convex lens at two different positions separated by 20 cm. 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.

An object 50 cm tall is placed on the principle axis of a convex lens. Its 20 cm tall image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of the lens.

An object 50 cm tall is placed on the principal axis of a convex lens. Its 20 cm tall image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal lengths of the lens.

An object 50 cm tall is placed on the principal axis of a convex lens. Its 20 cm tall image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of the lens.