PHASE 4: Determine index of refraction of prism Use the angle of refraction when the 70 80 90 angle of incidence is 40.0 degrees. 80 70 60 60 Assume that the index of refraction 50 50 of the air is 1.00. For each color of 40 40 light, complete the following steps: 30 1. Use Snell's law of refraction to 30 20 10 10 20 determine index of refraction of prism for color of light - - Normal 2. Record in Lab Data to 3 decimal O places 10 Blue (460 nm wavelength) light 40 2 Green (545 nm wavelength) light 3 Red (740 nm wavelength) light +Lab Data - X Angle of Refraction Angle of Blue Green Incidence Red Light Light Light (degrees) 40.0 67.9 67 66.5 30.0 46.1 45.7 45.5 20.0 29.5 29.3 29.1 Index of Refraction Blue Light Green Light Red Light Critical Angle Blue Green Red Light Light Light Measured (degrees) Calculated (degrees) HelpHelp X . Snell's law of refration is: n1 sin O1 = n2 sin 02 where n1 and n2 are the indices of refraction, and Oj and O2 are the angles of incidence and refraction. . Medium 1 = air, medium 2 = prism If n1 = 1.00, then sin O1 = n2 sin O2 . Solve for n2 sin O1 n2 = sin O2 . Total Internal Reflection If O2 = 90.0 degrees, then ni sin O1 = n2 . Solve for O1 O1 = sin-1 n2 n1 = critical angle . Medium 1 = prism, medium 2 = air If n2 = 1.00, then O1 = sin (11) = critical angleINTRODUCTION LABORATORY SIMULATION (@ Key Concepts The index of refraction of a transparent material is defined as the ratio of the speed of light in vacuum to the speed of light in the transparent material. When light is incident on the boundary between two transparent materials with different indices of refraction, some or none of the light crosses the boundary, and some or all of the light bounces back without crossing the boundary. Refraction is when the light crosses the boundary, and reflection is when the light bounces back without crossing the boundary. Snell's law of refraction can be used to determine the direction light travels after crossing the boundary between two transparent materials with different indices of refraction. Chromatic dispersion occurs because the index of refraction depends on the wavelength of the light. For some angles of incidence, all of the light is reflected and none of it is refracted. This is called total internal reflection. @ overview You will use a semicircular prism mounted on a protractor table that can be rotated, a white light source with three colored filters, and a slit mask that produces a narrow beam of colored light onto the protractor table. This setup ensures a perpendicular entry of the light from the air into the prism. The light does not change direction as it passes from the air into the prism. When the light is incident on the back surface of the prism, some or all of it is reflected and some or none of it is refracted, depending on the direction the light is moving. You will measure the angles of incidence and refraction for three different colors of monochromatic light. You will use Snell's law of refraction to determine the index of refraction of the prism for the three different colors of monochromatic light. You will measure the critical angle for the three different colors of monochromatic light. () Before you begin Snell's law of refraction is m1 sin ; = ngysin 2 where n1 and ny are the indices of refraction, and ; and 2 are the angles of incidence and refraction. The angles of incidence and refraction are measured between the direction the light is moving and a line perpendicular to the boundary between the two transparent materials. n = /v where = the speed of light in vacuum and v = the speed of light in the transparent material. In this lab, n(air) = 1.00. The formula for the critical angle can be derived from Snell's law of refraction by setting the angle of refraction equal to 90.0 degrees and solving for the angle of incidence. When the angle of incidence is greater than the critical angle, all of the light is reflected and none of it is refracted