1. 23 Electromagnetic Waves

2. Principle Faraday’s law: time-varying B-field creates E-field (emf) Maxwell: time-varying E-field generates B-field (emf) EM waves were PREDICTED by J.C. Maxwell in 1865. Light is part of the EM wave Heitz first detected the EM waves in 1887 after Maxwell died (1879). Another great prediction(s) was made by Einstein from his General Relativity. James C Maxwell British Scientist (1831 – 1879) Heinrich R Hertz German physicist (1857 –1894)

3. Properties of EM Waves 1.Transverse Wave; Both E & B perpendicular to propagation, k. E, B and k follow the right- hand rule 2.EM waves can be created and travel in vacuum (no medium required) with unchanging speed c 3.E & B are in phase and E= cB (in vacuum) v = f

4. EM Spectrum

5. Images Taken in Different EM Wave Regions

6. Sinusoidal Waves

7. Energy in EM Waves S: energy per unit area per unit time or power per unit area and the average value, S av called intensity, I.

8. Radiation Pressure

9. Nature of Light: Wave-Particle Duality

10. Wave Fronts Geometric optics & Physical Optics Rays & Waves

11. Reflection & Refraction

12. Index of Refraction & Snell’s Law Normal Incident Reflection Refraction aa rr bb Angles respect to normal line All the rays in same plane nanbnanb

13. Experience: Driving & Reflections

14. Value of Refractive Index Air 1.0003

15. Total Internal Reflection Critical angle: when  b = 90 o,  a =  c = sin -1 (n a /n b ) 90 cc

16. Dispersion: n= n( )

17. Polarization Linear polarization Circular polarization (left)

18. Mirage, Blue Sky, & Traffic Lights

19. Summary: EM Waves, Speed & Spectrum

20. Sinusoidal Waves and Energy

21. Nature of Light

22. Reflection & Refraction Total Internal Reflection:

23. Reflection & Refraction: Animations Animation of Refraction (rays) Animation of Refraction (waves)

24. Dispersion

25. Polarization

26. Homework Ch 23 Problems: 3, 6, 13, 20, 26, 38, 45, and 49

27. Test III Score Distribution Correct Points Number of Students Your grade =points/16x100%