Question

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1. If the speed of light changes to one third of its value entering from air to another medium, what is the refractive index of that medium with respect to air (nair-1) 3.0 A) B) 0.5 С) 2.0 D) Can't be determined from the information given. 2. Carbon disulfide (n, 1.63) is poured into a container made of crown glass (n2-1.49). What is the critical angle for internal reflection of a ray in the liquid when it is incident on the liquid-to-glass surface?(5) 3. Working Problem (show all your work) 10 Following is a plot of sin Oxetrac Vs sin On based on the data as light ray travels from air to glass. Here, Brefre represents the angle of refraction and 6,n represents the angle of incidence. 0.8 0.6 0.4 0.2 0. 0.2 y 0.6373x+3E-16 b 0.2 0.40.60.8 1 1.2 Sin0in Figure 1: sin Brefrac Vs sin 8in plot Explain in details how and why the equation of the line on the plot can be used to find refractive index of glass. What is the value of experimental index of refraction of glass ? a) b) 1. The focal length of a converging lens is determined through image formation. If focal length is 10 cm and the image distance is 16 cm, where is the object located at ? 2. Working Problem (show all your work) 15) Two converging lenses (fi-100 mm; f, 240 mm) are used to form an image of a candle on an observation screen. The distance between the lenses is kept small and is measured to be 3.7 cm. The distance of the candle from the center of both lenses is measured to be 12.5 cm. The distance of the image from the center of both lenses to the screen is measured to be 23 cm. a) What is the experimental focal length of the two combined lenses (in mm)? b) What is the theoretical focal length of the two combined lenses (in mm)? C) Would you see any image on the screen if the first lens of the combination is diverging (fi or why not? -100 mm)? Why yes Diffraction of Laser Light (15 slit width L What you expect in the interference fringe pattermns in a Young's double slit experiment if we change the slit w (d). Explain your answer. (5)

Answer 1

l_1 = speed in vacuum/speed in medium l_1 = c/c/3 = 3 rightarrow (A) n_1 = 1.63 n_2 = 1.49 for Total internal reflection, n_1 sin theta_e = (1.49) times sin 90 sin theta_e = 1.49/1.63 rightdoublearrow theta_e = 66.07 degree from graph, Straight line from snell's law, n_1 sin theta_in = n_2 sin theta_rad sin theta_ref = n_1/n_2 sin theta_in { from to glass n_1 = 1 Slope of graph will gives, 1/n_2 n_2 = of glass. tan theta = 0.6/ rightdoublearrow n_2 = 1/0.6 = 1.67 f = Converging lens f = 10 cm. V = 16 cm two possible cases image is real. 1/v - 1/f = 1/u rightdoublearrow 1/u = 1/16 - 1/10 = -6/16 times 10 u = -160/6 = -26.6 cm behind lens is virtual, v = -16 cm 1/u = -1/16 -1/10 = -26/16 times 10 u = -6.15 cm