If the distance between the screen and object is 50 cm and the displacement of the lens is 10 cm,clculate the focal length of the lens.

The graph between object distance u and image distance v for a lens is given below. The focal length of the lens is. .

The size of the image of an object,which is at infinity, as formed by a convex lens of focal length 30 cm is 2 cm. If a concave lens of focal length 20 cm is placed between the convex lens and the image at a distance of 26 cm from the convex lens, calculate the new size of the image

A needle placed 45cm from a lens forms an image on the screen placed 90cm on the other side of the lens. What is the type of lens ? Find the focal length. If the length of needle is 5cm. What is the length of image ?

The image obtained iwth a convex lewns is ereect and its length is four times the length of the object.If the focal length of the lens is 20 cm,calculate the object and image distance.

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

The image obtained with a convex lens is erect and its lenth is four times the length of the object.If the focal length of the lens is 20 cm,calculate the object and image distance.

A convex lens is used to obtain a magnified image of an object on a screen 10 m from the lens .If the magnification is 19,find the foal length of the lens.