Question

A concave mirror has a focal length of 25.8 cm. The distance between an object and its image is 33.9 m. Find (a) the object and (b) image distances, assuming that the object lies beyond the center of curvature and (c) the object and (d) image distances, assuming that the object lies between the focal point and the mirror. (a) Number Units (b) Number 1 Units (c) Number Units (d) Number 1 Units

Answer 1

sdi- given the beteren object and imagebb-+ 33.9emek If object is beyond the center of curvat- - ure, image will be real and positive [concave) So, as given do-d; = 33.9 cm » di = (8.-33.9) cm ③ Now using lens equation i = 1 + do > 3o - to-339 + do (do -33.9) = 30 (do + do -33.9) 3 do -33.9d. = 60 do -1017 3d? - 93.9 do +1017 = 0 » solking above quadratic equation we get 'do -12.49 (m) do -81.40 so if object distance, do=81.4cm, then image dislance is : di = 81.4-33.9. (en) di = 47. 5cm] and image is real and inverted: Now if do = 12.49 then d; = 12-49-33.9 di = -21.41 cm So, for do=12.49, then it is between focal . point and mirror. . And image is negative (-21-41cm) Answers: A do =81.4cm Bd; = 47. 5cm c) do.=12:49emi D d; = -21.41cm please RATE my Any - .