Consider a point at the focal point of a convergent lens. Another convergent lens of short focal length is placed on the other side. What is the nature of the wavefronts emerging from the final image?

An upright object is placed at a distance of 40 cm in front of a convergent lens of focal length 20 cm. A convergent mirror of focal length 10 cm is placed at a distance of 60 cm on the other side of the lens. The position and size of the final image will be:

The focal length of a convex lens is 20 cm.What is the power?

Two thin converging lenses of focal length 15 cm and 30 cm are held in contact with each other. The focal length of the combination is

A concave lens of focal length f produces an image (1)/(4) of the size of the object, the object should be kept at ____ from the lens.

An object is placed at a distance of 10cm from a convex lens of focal length 12cm.Find the position and nature of the image.

An object is kept at 60 cm in front of a convex lens of focal length 15 cm . Find the image distance and the nature of the image . Also find the magnification produced by the lens.

Graph of position of image vs position of point object from a convex lens is shown. Then, focal length of the lens is

A comvex lens and a concave lens are placed in contact. The ratio of magnitude of the power of the convex lens to that of the concave lens is 4:3. If the focal length of the convex lens is 12 cm, then the focal length of the combination will be