Lab 17- Lab Report

Cailinn Hilliard 2 Purpose To study the Law of Reflection. To study the Law of Refraction. To measure the index of refraction of lucite. Theory Law of Reflection. When a beam of light is incident on a surface as shown in figure 17.1, its angle of incidence is measured from the normal as 𝛳 r , which is also measured from the normal. The law of Reflection states that the angle of reflection equals the angle of incidence, which may also be written in equation form: 𝛳 r = 𝛳 i Law of Refraction. When a beam of light is incident on the surface of a medium that is different than the incident medium, its path direction changes as shown in figure 17.2. The direction change is called refraction. The change in direction is explained by the law of refraction which is also known as Snell's Law. Snell's Law in equation form is written as N r sin 𝛳 = n i sin 𝛳 where n r and n i are the indices of refraction of the refracting and incident media, respectively, and 𝛳 r and 𝛳 i are the angles of refraction and incidence, respectively. The index of refraction of any medium is defined by the ratio of the speed of light in a vacuum so that in the medium or ? = ????? ?? ?𝑖?ℎ? 𝑖? 𝑎 ?𝑎???? ????? ?? ?𝑖?ℎ? 𝑖? 𝑎 ???𝑖?? = ? ? The speed of light in a medium is always less than that its speed in a vacuum. Therefore, the index of refraction of every non-vacuum medium is greater than 1.0. As a practical matter, the speed of light in air is very close to the speed in a vacuum. Therefore, the index of refraction of air is assumed to have the same index as a vacuum, 1.0. For this experiment, the index of refraction of lucite can be determined using the following expression: = ? ?𝑖?𝛳𝑖 ?𝑖?Θ? Apparatus Lightbox, mirror, lucite block, paper, protractor, and straightedge. Procedure 1. Tape a sheet of paper to your tabletop. Use a straightedge to draw a line down the length of the paper lengthwise and near one edge. Draw a perpendicular line (normal) across the center of the page which intersects the first line.