A camera lens of focal length of 20mm forms an image on the focal plane that is twice the size of the object. What are the object and image distance

A sharp image of a pencil that’s 25 cm away from your eye is formed on your retina. As you move the pencil farther away from your eye, what happens to the lens of your eye in order to form a sharp image on the retina?       It gets less curved, increasing its focal length     It gets less curved, decreasing its focal length     It does not change       It gets more curved, increasing its focal length     It gets more curved, decreasing its focal length

Object is placed 35cm from a convex lens whose focal length is 15cm. Find the location of the image formed by the lens and the magnification of the image.

A convex lens produces an image with a magnification of +5. Describe the locatior size, and orientation of the image produced. Circle one from each pair of answers Same side as object/ opposite side as object Upright/Inverted Real /Virtual Enlarged /Reduced

An object is placed 25cm from a concave mirror with a radius of curvature of 15cm. Find the image distance and the magnification of the object.

a ray diagram for eyeglasses that contain a converging lens. Assume you are looking at a 2 cm tall object that is 4 cm from the lens. The focal length is 3 cm

Famous jeweler Gabi Tolkowsky is looking at a 3.0-cm-tall perfect oval-shaped diamond through a thin lens. The diamond is 20.0 cm behind the lens, and the distance between its upright image and the lens is 40.0 cm. What is the focal length of the lens? Is it converging or diverging? How tall is the image? 
 PLEASE PLEASE draw a ray diagram and define variables

The (converging) objective lens of a telescope has a focal length of 0.84 m. An object is located at a distance of 12m from the lens. At what distance from the objective lens is the image formed by this lens ? Give your answer in meters