Index of Refraction of Various Household Liquids
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Refraction is the bending of incident rays due to a reduced speed in a particular medium. The index of refraction is the ratio of the speed of light to the speed of light through a particular medium or n = c/v. The index of refraction in a vacuum is 1. There can be no index smaller than one. The index of refraction in air is 1.000277.
To determine the index of refraction we filled a semi-circular tray with vinegar. The tray was then placed on this page (pdf page 2 of 2) within the outline of the semicircle. A pin was placed at the center of the semi-circle. A second pin as then placed at the 5 degree refracted ray. Looking in from the curved side close one eye and move your head until the second pin lines up with the first pin when viewed through the liquid. Take a third pin and place it on the opposite side of the tray so that all the pins line up. Repeat this step for 10, 15, 20, 25 degrees, etc. until you are unable to align all three pins. Once you have completed all the angles possible, draw straight lines from the center of the semicircle through each of the pinholes, to the end of the page. Then with a protractor, measure the angle from the y axis on the sheet and record on the chart below. Do two trials for the following substances: Heinz Vinegar, Key Food Honey, Orange Pine-Sol, Nyquil Chloraseptic, and Earth Therapeutic Foot Wash.
Complete a graph of the sines: the sine of the angle of incidence on the x-axis and the sine of the angle of refraction on the y-axis. Make a best fit line of the graph. The sines are directly proportional, so the slope of the best fit line is the index of refraction for that particular substance. We completed two trials for each of the liquids, and then took their averages.
| θ1 (°) | θ2 (°) | sinθ1 | sinθ2 |
|---|---|---|---|
| 5 | 7 | 0.08716 | 0.12187 |
| 10 | 13 | 0.17365 | 0.22495 |
| 15 | 20 | 0.25882 | 0.34202 |
| 20 | 28 | 0.34202 | 0.46947 |
| 25 | 34 | 0.42262 | 0.55919 |
| 30 | 40 | 0.50000 | 0.64279 |
| 35 | 47 | 0.57358 | 0.73135 |
| 40 | 57 | 0.64279 | 0.83867 |
| 45 | 63 | 0.70711 | 0.89101 |
| θ1 (°) | θ2 (°) | sinθ1 | sinθ2 |
|---|---|---|---|
| 5 | 5 | 0.08715 | 0.08716 |
| 10 | 14 | 0.17365 | 0.24192 |
| 15 | 20 | 0.25882 | 0.34202 |
| 20 | 30 | 0.34202 | 0.5 |
| 25 | 38 | 0.42262 | 0.61567 |
| 30 | 47 | 0.50000 | 0.73135 |
| 35 | 58 | 0.57358 | 0.84805 |
| 40 | 63 | 0.64279 | 0.89101 |
| θ1 (°) | θ2 (°) | sinθ1 | sinθ2 |
|---|---|---|---|
| 5 | 7 | 0.08716 | 0.12187 |
| 10 | 12 | 0.17365 | 0.20791 |
| 15 | 21 | 0.25882 | 0.35837 |
| 20 | 28 | 0.34202 | 0.46947 |
| 25 | 36 | 0.42262 | 0.58779 |
| 30 | 43 | 0.50000 | 0.68199 |
| 35 | 50 | 0.57358 | 0.76604 |
| 40 | 60 | 0.64279 | 0.86603 |
| 45 | 68 | 0.70711 | 0.92718 |
| θ1 (°) | θ2 (°) | sinθ1 | sinθ2 |
|---|---|---|---|
| 5 | 9 | 0.08716 | 0.15643 |
| 10 | 18 | 0.17365 | 0.30902 |
| 15 | 26 | 0.25882 | 0.43837 |
| 20 | 32 | 0.34202 | 0.52992 |
| 25 | 39 | 0.42262 | 0.62932 |
| 30 | 49 | 0.50000 | 0.75472 |
| 35 | 55 | 0.57358 | 0.81915 |
| 40 | 58 | 0.64279 | 0.84805 |
| 45 | 62 | 0.70711 | 0.88295 |
| θ1 (°) | θ2 (°) | sinθ1 | sinθ2 |
|---|---|---|---|
| 5 | 8 | 0.08716 | 0.13917 |
| 10 | 16 | 0.17365 | 0.27564 |
| 15 | 22 | 0.25882 | 0.37461 |
| 20 | 29 | 0.34202 | 0.48481 |
| 25 | 35 | 0.42262 | 0.57358 |
| 30 | 41 | 0.50000 | 0.65606 |
| 35 | 53 | 0.57358 | 0.79864 |
| 40 | 60 | 0.64279 | 0.86603 |
Africa Belgrave, Geeta Malieckal, Bridget Ritter -- 2005