The image obtained with a convex lens is erect and its length is `4` times the length of the object. If the focal length of lens is `20 cm`, calculate the object and image distances.

The image obtained with a convex lens is erect and its length is 4 times the length of the object. If focal length of the lens is 20cm , calculate the object and image distances.

A real image is obtained at 30 cm from a convex lens of focal length 7.5 cm . Find the distance of the object from the lens .

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

The focal length of a convex lens is 30cm and the size of the real image is (1)/(4)th of the object. Then the object distance is

The focal length of convex lens is 30 cm and the size of image is quarter of the object, then the object distance is

A convex lens and a convex mirror are separated by a distance of 10 cm such that the reflecting surface of the mirror faces the lens. The image of an object placed in front of the convex. Lens at a distance of 20 cm is found to coincide with the object. If the focal length of the convex lens is 15 cm, determine the focal length of the mierror.

A lens of focal length 12 cm forms an upright image three times the size of a real object. Find the distance in cm between the object and image.

The same size images are formed by a convex lens when the object is placed at 20cm or at 10cm from the lens. The focal length of convex lens is ____ cm