PHYS 223 Final, Spring 1997

Final Exam Physics 223 16 June 1997 I--- A plano-convex lens(7 = 1.50; radius of curvature = 3.00m) rests on a flat glass plate of n= 1.60 (Fig. 1). Newton's rings are observed in the air wedge (index nz ) by reflected red light of 4 = 632.8 nm at normal incidence. 1. (a) Find in terms of 4, R and n2 the radius x; of the k® dark fringe. (b) Find the color of the central fringe; (c) Calculate the radius of the 10" dark fringe; 2. If liquid of index n =1.55 fills up wedge between lens and plate, find the (a) Color of the central fringe; (b) Order and color of fringe having same radius as fringe 1(c). 3. Consider the basic setup ( fig.1). Raise the lens perpendicularly by a distance t, = 1.01 above the plate, find: (a) order and color at center (b) radius of first dark fringe (c) Order and radius of 10" dark fringe. Il- Natural light is incident at 75° on a plane parallel plate of glass(n = 1.56). Find the degree of polarization of the light transmitted through the plate. II- A monochromatic plane wave of natural light is incident on a crystalline flat plate of thickness t = 1.0 cm and indices ng = 1.544 & ne = 1.553 (Fig. 2). 1. Using Huygens’ construction trace the refracted rays with vibration directions. 2. If the reflected light is completely linearly polarized, find: (a) The angle of incidence i (b) The lateral, perpendicular separation of the emerging rays. ra cosi — n, cosr — Nn, COSi — , COST +t 2n, cosi 2n, cosi i” ; on . ae ; oft = - n, COSi + m, COST n, COSi + m, Cosr n, COSi +n, COST u n, COSY + My COSI