19.The filament of a lamp is `80cm` from a screen and a converging lens forms an image of it on a screen magnified three times.Find the distance of the lens from the filament and the focal length of the lens.-

An object 2 cm tall is placed on the axis of a convex lens of focal length 5 cm at a distance of 10 m from the optical center of the lens. Find the nature, position and size of the image formed. Which case of image formation three times. Find the distance of the lens from the filament and the focal length of the lens.

A converging lens is to projected image of a lamp 4 times the size of the lamp on a wall at a distance of 10m from the lamp. The focal length of the lens is

An object placed at 20 cm from a lens, forms an image on a screen placed 60 cm on the other side of the lens. What is the focal length and type of the lens ?

A convex lens is used to obtain a magnified image of an object on a screen . The object is at a distance 10 m from the lens . If the magnification is 19. the focal length of the lens is

A candle placed 25 cm from a lens, forms an image on a screen placed 75 cm on the other end of the lens. The focal length and type of the lens should be

A convex lens produces an inverted image magnified three times of an object placed of 15 cm from it. Calculate focal length of the lens.

A needle of height 5 cm placed 45 cm from a lens forms an image on a screen placed 90 cm on the other side of the lens the type of lens and its focal length are

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 length of the lens.