1. UCSD Physics 10

2. UCSD Physics 10

3. UCSD Physics 10 Winter 20043 Reflection Reflection off a flat surface follows a simpleReflection off a flat surface follows a simple LAW OF REFLECTION : LAW OF REFLECTION : –angle in (incidence) equals angle out –angles measured from surface “normal” (perpendicular) surface normal same angle incident ray exit ray

4. UCSD Physics 10 Winter 20044 Hall Mirror It is useful to think in terms of images and objectsIt is useful to think in terms of images and objects “image” of you The real “object” (you) mirror only needs to be half as high as you are tall. Your image will be twice as far from you as the mirror.

5. UCSD Physics 10

6. UCSD Physics 10 Winter 20046 Refraction Light also goes through some thingsLight also goes through some things –glass, water, eyeball, air Presence of material slows light’s progressPresence of material slows light’s progress –interactions with electrical properties of atoms Light has slowing and bending factor called the index of refraction. The denser it is the higher the index and the more it slows and bends lightLight has slowing and bending factor called the index of refraction. The denser it is the higher the index and the more it slows and bends light –glass has n = 1.52, meaning that light travels about 1.5 times slower in glass than in vacuum –water has n = 1.33 –air has n = 1.00028 –vacuum is n = 1.00000 (speed of light at full capacity)

7. UCSD Physics 10 Winter 20047 The index of refraction tells how many times slower an object travels when passing into the denser substanceThe index of refraction tells how many times slower an object travels when passing into the denser substance Find the speed of light through corn oil.

8. UCSD Physics 10 Winter 20048 n 2 = 1.5 n 1 = 1.0 A B Refraction at a plane surface Light bends at interface between refractive indicesLight bends at interface between refractive indices 11 22

9. UCSD Physics 10 When light goes into a denser material it bends ____________ the normal When light goes into a less dense material it bends ____________ the normal

10. UCSD Physics 10

11. UCSD Physics 10 Snell’s Law

12. UCSD Physics 10 Winter 200412 Snell’s Law