A 1 cm object is placed perpendicular to the principal axis of a convex mirror of focal length 7.5 cm . Determine its distance from the mirror if the resulting image is 0.6 cm in size.

Step-by-step solution

Given h_ o = 1 cm , f = +7.5 cm , and h_ i = +0.6 cm (virtual and erect image for a convex mirror). Magnification m = h_ i h_ o = 0.6 1 = 0.6 Using m = - v u , we get v = -0.6u . Applying the mirror formula: 1 v + 1 u = 1 f 1 -0.6u + 1 u = 1 7.5 -1 + 0.6 0.6u = 1 7.5 -0.4 0.6u = 1 7.5 -2 3u = 1 7.5 3u = -15 u = -5 cm The distance of the object from the mirror is 5 cm .