13.1 Young's experiment is performed with orange light from a krypton arc. If the fringes are measured with a micrometer eyepiece at a distance 100 cm from the double slit, it is found that 25 of them occupy a distance of 12.87 mm between centers. Find the distance between the centers of the two slits. Ans. 1.1297 mm13.2 A double slit with a separation of 0.250 mm between centers is illuminated with green light from a cadmium-arc lamp. How far behind the slits must one go to measure the fringe separation and find it to be 0.80 mm between centers?13.6 A Fresnel biprism of index 1.7320 and with apex angles of 0.850 is used to form interference fringes. Find the fringe separation for red light of wavelength 6563 A when the distance between the slit and the prism is 25.0 cm and that between the prism and the screen is 75.0 cm.$3.? what must he the angle in degrees between the two Fresnel mirrors in urderto produce sodium light fringes 1.0 mm apart if the slit is 40.0 cm frOm the mirror inter- section and the semen is 150.0 cm from the slit? Assume .1 = 5.893 x 10-5 cm. Ans. 0.06331\