(a) Table 1: Calculate the focal length using the Lens equation and complete the table give (Write three digits after the decimal for each value) 1 1 u (cm) (cm1) u v (cm) (cm*1) V f (cm) 15 31 18 23.5 21 20 17.5 16 Mean focal length of the convex lens f: cm (b) Calculate Power of the lens : (Write the answer with the unit in the spaces given) 24 27

An illuminated slide is held 44 cm from a screen. How far from the slide (between the slide and the screen) must a lens of focal length 6.4 cm be placed to form an image of the slide's picture on the screen? (Give the smaller of the two possible answers.) Number Units

(Dove Prism) A new type of prism inverts an image that comes in through one end (see Figure 1). The prism will be shaped like a trapezoid with a square cross-section and sides cut at a 45° angle, and that the prism will be made of a plastic called BK7 that has an index of refraction of 1.517. Decide on the dimensions of the prism in order to maximize the size of the image that can be inverted (see incoming/outgoing rays in the side view in Figure 2). How long (length B in Figure 1) should the prism be in terms of its height (length A in Figure 1)? What happens to an image that enters the prism on one side of its long face (see figure 3)? Make a drawing tracing the path of rays 4, 5, and 6 in figure 3 to find out. Figure 1 Figure 2 1 3 2 45° 3 1 Figure 2 Figure 3 45° Figure 3 4 5 6

= 1.0). An object (A) is Assume that a thin lens (r, placed in the left side of lens (d = 45mm) and the image of the object is located in the right side of the lens at position (B) (d' = 90mm). 1) Compute the refraction index of the lens (n2); = -r2 = 40mm) is placed in the air (n 2) If placing another negative thin lens (f2 = -180mm) immediately behind the first lens to create a doublet lens in which the spacing between two lenses is zero (as shown in the right figure), what is the focal length of this doublet? 3) Where is the final image position (C) of the object (A) through this new doublet? (Note: Assuming this doublet lens is a combined thin lens too without considering its thickness).