Show that the distance between a real object and its real image formed by a thin converging lens is always greater than or equal to four times the focal length of the lens.

The minimum distance between an object and its real image formed by a convex lens is

The minimum distance between an object and its real image formed by a convex lens is

The minimum distance between a real object and its real image formed by a thin converging lens of focal length f is

The minimum distance between an object and its real image formed by a thin convex lens of focal length f is K.f . Find the value of K .

The distance between the object and its real image from the convex lens is 60 cm and the height of image is two times the height of object . The focal length of the lens is

Choose the correct alternative corresponding to the object distance 'u', image distance 'v' and the focal length 'F' of a converging lens from the following . The average speed of the image as the object moves with the uniform speed from distance (3F)/(4) to (F)/(2) is greater than the average speed of the image as the object moves with same speed from distance (F)/(2) "to" (F)/(4) The minimum distance between a real object and its real image in case of a converging lens is 4F where F is its focal length.

Shown an object and its image formed by a thin lens. Then the nature and focal length of lens is

Choose the following statement a True of False. a. The real image formed by a lens is always inverted. b. The image formed by a lens is always inverted. c. The image formed by a concave lens is always erect and diminished. d. An air bubble inside water acts like a concave lens. e. The distance between a real object and its real image formed by a single lens cannot be more than 4f. f. I an object is moved at a constant speed toward a convex lens from infinity to focus, then its image moves slower in the begninning and faster later on, away from the lens. g. The focal length of a glass (mu=1.5) lens is 10 cm in air. When it is completely immersed in water its focal length will become 40cm.

An object is kept at rest on the principal axis of a lens. Initially the object is at a distance three times the focal length 'f' of the lens. The lens runs towards the object at a constant speed u, until the distance between the object and its real image becomes 4 f . If the iamge always forms on a moving screen then express the velocity of the screen as a function of time.

Distance of an object from the first focus of an equi-convex lens is 10 cm and the distance of its real image from second focus is 40 cm. The focal length of the lens is