Question

A converging lens has a focal length of 10.0cm. Construct accurate ray diagrams for object distances of (i) 20.0cm and (ii) 5.00cm. (a) From your ray diagrams, determine the location of each image. (b) Is the image real or virtual? (c) Is the image upright or inverted? (d) What is the magnification of the image? (e) Compare your resstuls with the value found algebraically. (f) Comment on difficulties in constructing the graph that could lead to difference between the graphical and algebraic answers.

Answer 1

Lens. F= 10 cm ;) Focal length of the converging object distance ,u = 2F 20 em A B F2 2F2 F 25 0 B' 22 s 4 Og will mays - Here, object AB is at 2F. First we draw a may parallel to principal axis, which passes through F2 after refraction. Another pay which passes through optical center go through without any deviation. Both refracted meet at point A and image formed is M'B'. The image is formed at 2F2. b) from above figure we see that the netracted mays actually meet at point A'. so, the image eo From may diagram we see that the image is formed at the lower side of the principal axis so, the image is inrested. d) Image is exactly the same size as that of object. so, magnefication is one. Magnification, m= Image distance (re) Object distaneely) image is real. 20 cm = 20 cm

i) Focal Length of the conve nyenging lens,F=10 cm Object distance, 4 = 5 em = 5 a) B' F2 B QF ud k 20 ع کیا draw will see, is A'B. Hene, object AB is kept at 5em from óptical centeno, ie object is in the middle between O and F. First, a may parallel to principal axis, which passes therough focus F, after refraction. Another may which passes through o, go through without any deviation. We both refracted rays are divenging. It means that they would have met at some point. Hence, we extend both rays behind the lens. The says form an image behind the lens and image formed Image is formed at Fi (behind the lens) b) we see that the mefracted pays don't actually meet at A' mather than appearing from A'. vintual, image is formed at the upper side of the principal axis. so, the image is upright. a) Image is zanger than the object ie magnified. greater than one. Magnificationim = Image distance (v) objeet distance luz = 2 so, the image is e) The so, magnification is 10 em 5 em
If the refracted rays actually meet at a point, the image formed will be real. If the refracted rays appearing from a point, the image formed will be virtual.