Snell's Law states that the angle of an incident light ray relative to the normal of a boundary between two substances is related to the angle of the refracted light ray by the following relationship ni sin 01 = n2 sin 02 If a ray of light traveling from a medium of greater index of refraction to a medium of lesser index of refraction is incident with an angle greater than the critical angle (0c), there is no refracted ray and total internal reflection occurs. 1. CALCULATE THE CRITICAL ANGLE. If the angle of incidence is exactly the critical angle, the angle of the refracted ray is 90 degrees. In this case, using Snell's Law, n sin 0c = (1) sin (90). Assume the index of refraction of air, nair = 1 and the acrylic Rhombus, nacrylic = 1.5. 2. FIND THE EXPERIMENTAL CRITICAL ANGLE Place the cylindrical lens on the ray table as shown below. Rotate the ray table to observe what happens as the critical angle is approached. a. How does the brightness of the internally reflected ray change when the incident angle changes from less than Oc to greater than ec? b. How did your calculation compare to the experimental critical angle? Light c. Draw and label the following for a ray at an angle source less than the critical angle incident ray reflected ray . refracted ray normal 01 = angle of incidence sib evode al . 2 = angle of reflection 93 = angle of refraction component d. Draw and label the following for a ray Light at the critical angle : source incident ray . reflected ray . refracted ray 01 = angle of incidence normal 02 = angle of reflection 03 = angle of refraction component"LAB # 4" THE DISPERSION OF LIGHT INTO A "RAINBOW" Names: In this lab segment you will use the prism to act as a "raindrop" and separate white light into a "rainbow". Adjust the position of the prism so that you get the widest dispersion of color in your "rainbow". Look nearby sheet of white paper to see the rainbow Make a sketch of what you observe. Use dots to mark the path of light beam into the prism, where the beam exits the prism, and both edges of your "rainbow" as far from the prism as is possible on a single sheet of paper. Label the incoming light beam, the prism, your "rainbow", the position of the violet light, and the position of the red light. THE DISPERSION OF LIGHT INTO A "RAINBOW" Incoming beam in air outgoing beam Light In air o engl in source gro Insbioni end Acrylic prism QUESTIONS 1. In above diagram, draw and label the following: normal line for incoming beam 1 st refracted beam from air to acrylic normal line for outgoing beam 2nd refracted beam from acrylic to air (draw the red beam and the violet beam) 2 . What color of light is refracted the most? 3. What color of light is refracted the least