Lab 9. Reflection and Refraction

Reflection and Refraction Reflection and refraction are two commonly observed optical properties of light. Whenever light strikes the surface of some material at an angle, part of the wave is reflected, and part is transmitted (or absorbed). The reflection of light rays from a plane surface such as a glass plate or a plane mirror is described by the law of reflection : Law of reflection : θ i = θ r The angle of incidence (θ i ) is equal to the angle of reflection (θ r ). These angles are measured from a line perpendicular or normal to the reflecting surface. Refraction : represents a change of direction that light undergoes when it enters a medium with a different index of refraction from the one through which it has been traveling — for example, when, after moving through air, it passes through water . Law of Refraction: n 1 sin 𝜃 1 = n 2 sin 𝜃 2

n 1 = index of first material 𝜃 1 = angle of incidence n 2 = index of second material 𝜃 2 = angle of refraction Procedure The lab activity uses a simulation developed by the University of Colorado at Colorado Boulder. Refraction and Reflection Click here Choose “Intro” A. 1.Select Material 1 [top Material] is Air 2.Index of Refraction is n 1 =1 3.Select Material 2 [Bottom Material] is Water 4.Click on Red button, 5.Use protractor and adjust the angel of incidence 𝜃 1 = 30 0 6.Record in the table n 2 and 𝜃r and 𝜃 2 Material 1: Air n 1 = 1 𝜃 1 = 30 0 𝜃 1 = 30 0 Material 2: Water n 2 = 1.33 𝜃r = 30° 𝜃 2 = 22.62° Q1. What is happening with the laser beam at the interface between air and water? Are both reflection and refraction laws verified? The laser beam is partially reflecting into the air and the rest of the beam is in the water and bending due to refraction. B. Repeat steps 1 to 5 but adjust the mediums and angles to the values indicated in the table below. Material 1: Air n 1 = 1 𝜃 1 = 30 0 𝜃 1 = 30 0 Material 2: Glass n 2 = 1.50 𝜃r = 30° 𝜃 2 = 19.47°