Angular Magnification In deriving Eq. (34.22) for the angular magnification of a magnifier, we assumed that the object is placed at the focal point of the magnifier so that the virtual image is formed at infinity. Suppose instead that the object is placed so that the virtual image appears at an average viewer's near point of 25cm, the closest point at which the viewer can bring an object into focus.
(a) Where should the object be placed to achieve this? Give your answer in terms of the magnifier focal length f
(b) What angle 0' will an object of height y subtend at the position found in part (a)?
(c) Find the angular magnification M with the object at the position found in part (a). The angle 0 is the same as in Fig. 34.51a, since it refers to viewing the object without the magnifier.
(d) For a convex lens with f = + 10.0 cm, what is the value of M with the object at the position found in part (a)? How many times greater is M in this case than in the case where the image is formed at infinity? (e) In the description of a compound microscope in Section 34.8, it is stated that in a properly designed instrument, the real image formed by the objective lies just inside the first focal point F1 of the eyepiece. What advantages are gained by having the image formed by the objective be just inside F1', as opposed to precisely at F1? What happens if the image formed by the objective is just outside F1?