EXPERIMENT: WATER REFRACTION OBJECTIVES Observe the refraction of light as it passes through water. Calculate and record an experimental refractive index of water. Compare the recorded experimental refractive index of water to the actual index of water. Click here for a List of Physical Constants sheet. In this investigation you will examine the refraction of light through water. These supplies are needed: semicircular plastic dish ruler protractor 15 pins sheet of graph paper corrugated cardboard Follow these directions and answer the questions. 1. Set up the apparatus as shown. 2. Fill the dish with water and place it on the corrugated cardboard mat covered with graph paper. 3. Place a pin (Pin #1) at the midpoint of the side and one (Pin #2) about 4 centimeters away, perpendicular to the other pin. 4. Trace the shape of the dish on the paper. 5. Look at the pins through the water (from the curved side of the dish by stooping down eye level to the dish). Align a third pin with the two pins you see through the water. 6. Mark these two locations (Pin #2 and Pin #3) with an "a." 7. Move Pin #2 to another location (either to the right or left) so that the incident ray, the line from Pin #2 to Pin #1, strikes the water at an angle. Follow the same procedure with Pin #3. 8. Label these points "b." 9. Repeat this procedure for at least four more locations (up to 80o angle of incidence). 10. Remove the dish and complete the circle (the dish is a half circle). 11. Draw lines from Pins #2 and #3 to Pin #1 (location 0). The lines represent rays of light from air through water. 12. Keeping track of which ray in air continues into the water, draw lines AC and FD (notice that AO and OD are the same length). 13. Label these lines ACa, ACb, ACc . . . and FDa, FDb . . The index of refraction, n, can be defined as The sine of an angle is the side opposite the angle divided by the hypotenuse. (These angles are measured with respect to the normal, that is, the line that is shared by both triangles and is perpendicula