How far from a 50.0-mm-focal-length lens must an object be placed if its image is to be magnified 3.50× and be virtual?

A 2.5 cm-tall object stands in front of a converging lens. It is desired that a virtual image 2.6 times larger than the object be formed by the lens. How far from the lens (in cm) must the object be placed to accomplish this task, if the final image is located 13 cm from the lens?  cm?

A slide projector has a converging lens whose focal length is 128.00 mm. (a) How far (in meters) from the lens must the screen be located if a slide is placed 129.44 mm from the lens? If the slide measures 24.0 mm (width) x 36.0 mm (height), what are the magnitudes of the (b) width (in mm) and (c) height (in mm) of its image? (a) Number i Units (b) Number i Units (c) Number i Units

An amateur astronomer decides to build a telescope from two lenses. One of the lenses has a focal length of 10.0 cm, and the other has a focal length of 1.4 cm. (a) Which lens should be the objective, for maximum magnification? (b) What will be the magnification of the telescope? (c) How long will the telescope tube be if the telescope is focused on a flower that is 1.00 meter away? (Keep four significant figures for this.)

A certain camera is able to focus on objects from 1.13 m to ∞o. Suppose you want to take an extreme close-up shot, with the camera 19 cm from the object. Find the focal length of a thin lens that could be placed directly in front of the camera lens such that the image of the close object would be in focus. (Let's denote the minimum and maximum values of the focal length by fmin and fmax, respectively.) 228 m -u I fmin = fmax = XX