1. Snell’s Law

2. Uses an equation that allows us to calculate how a ray of light will bend as it passes from one medium to another. Deals with the relationship between the angle of incidence and the angle of refraction of two media Applies to the refraction of light in any situation, regardless of what the two media are.

3. Snell’s Law n 2 = sinθ 1 n 1 sinθ 2 SymbolDescription n1n1 Index of refraction of medium 1 n2n2 Index of refraction of medium 2 sin θ 1 Angle of incidence sin θ 2 Angle of refraction

4. Snell’s Law Reorganized n 1 sinƟ 1 = n 2 sinƟ 2

5. Calculating Snell’s Law When light passes from air into water at an angle of 60° from the normal, what is the angle of refraction? Given: n 1 = 1.00 n 2 = 1.33 ϴ 1 = 60° For our given  must refer back to Refraction Notes Equation: Unknown: sinϴ 2 = ? sinϴ 2 = n 1 sinϴ 1 n 2 Solve : sinϴ 2 = (1.00)(sin60°) 1.33

6. Solve : sinϴ 2 = (1.00)(sin60°) 1.33 (enter into calculator: 1.00 x 60 sin / 1.33 ) sinϴ 2 = 0.6511 (enter into calculator: 0.6511 sin -1 ) ϴ 2 = 40.62° Statement: When light passes from air to water at an angle of 60 o, the angle of refraction is 40.62 o.

7. Example 2 Light enters vegetable oil from air. The incidence angle is 14° and the angle of refraction is 9.38°. What is the index of refraction for vegetable oil? Given: n 1 = 1.00 ϴ 1 = 14 o ϴ 2 = 9.38° Unknown: n 2 = ? Equation: n 2 = n 1 sinϴ 1 sinϴ 2 Solve : n 2 = 1.00 x sin 14 o sin 9.38 o

8. Statement: Therefore the index of refraction of vegetable oil is 1.48. [If you are not getting this value take a look at your calculator. Some calculators need you to put the number then hit sin.] Solve : n 2 = 1.00 x sin 14 o sin 9.38 o n 2 = 1.00 x 0.24192189 0.16298157 n 2 = 1.48435

9. Now work on the remaining examples

10. Interactive Links http://phet.colorado.edu/en/simulation/bend ing-light http://phet.colorado.edu/en/simulation/bend ing-light http://lectureonline.cl.msu.edu/~mmp/kap25 /Snell/app.htm http://lectureonline.cl.msu.edu/~mmp/kap25 /Snell/app.htm