Question

Chapter 34, Problem 062 Lenses with given radii. Object O stands in front of a thin lens, on the central axis. For this situation, each problem in the table (below) gives object distance p, index of refraction n of the lens, radius r 1 of the nearer lens surface, and radius r2 of the farther lens surface. (All distances are in centimeters.) Find (a) the image distance i and (b) the lateral magnification m of the object, including signs. Also, determine whether the image is (c) real or virtual, (d) inverted from object O or noninverted, and (e) on the same side of the lens as object O or on the opposite side. p n 11 r2 (a) i (b) m (c) R/V (d) I/NI (e) Side +20 1.60 +42 -42 (a) Number Units (b) Number Units @ @

Answer 1

a)Using Lens maker's formula The focal length of the lens is, = (16-1) 42 + = -0.02857cm f=-35cm The image distance is, Ipf p-f (20)(-35) 20-(-35) =-12.7cm (b)The magnification is, m=-9 (-12.7) 20 = 0.635 (c)Negative sign of the image distance indicates that the image is virtual. (d) Positive sign of the magnification indicates that the image is upright (e)A virtual image always lies on the same side as the object.