# Phy101 Lab 12

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Lab Title Geometrical Optics &amp; Snell's Law | Lab # 11 | Name: | Joseph Apap | Class: | PHY101-14995 | Date: | 07/29/2015 | Purpose: | * Explain how to experimentally determine the index of refraction of two substances. * Develop a set of experimental procedures to find the index of refraction for water and vegetable oil. * Calculate the index of refraction using Snell's Law. * Explain Critical angle and total internal reflection | Procedures: | Required Materials: | * Laser pointer * Refraction cell * Ruler * Protractor * Vegetable Oil * Water * Paper * Pencil | | Apparatus | | | 1. Draw parallel lines on a piece of paper. 2. Place Refraction Cell on piece of paper so flat side of Refraction cell lines up with vertical line on the piece of paper and the horizontal line (reference line) cuts the refraction cell in half. 3. Fill refraction cell with water. 4. Direct laser pointer at Refraction cell so that the light from the laser pointer enters the refraction cell at the reference line. 5. Place a dot on the piece of paper at the point where the laser light originates from the pointer and where it leaves the refraction cell after passing through the water. 6. Use a ruler to draw a line from the points placed on the paper to the point where the parallel lines intersect. 7. Use a protractor to measure the angle from the reference line to the lines drawn in step 6. 8. Record the angle created by the laser pointer through the air as the Angle of Instance and the angle created by the laser pointer through the water as the Angle of Refraction. 9. Use Snell's Law to determine the Index of Refraction of Water. 10. Empty and dry refraction cell and repeat step's 1-9 using the Vegetable Oil instead of water. | Results and evaluation of data: | 1.35 Using Snell's Law n1sinθ1=n2sin θ2 n1=1 (n of air is 1)