1. Electromagnetic Waves Maxwell`s Equations Lecture 23 Thursday: 8 April 2004

8. ELECTROMAGNETIC WAVES E = E m sin(kx -  t) B = B m sin(kx -  t)

11. POYNTING VECTOR This is a measure of power per area. Units are watts per meter 2. Direction is the direction in which the wave is moving.

12. POYNTING VECTOR However, since E and B are perpendicular,

13. INTENSITY

15. RADIATION PRESSURE

19. Comet: Picture taken WEDNESDAY 26 March 1997,at 2000 CST,at White Bear Lake,Minnesota.

20. MAXWELL’S EQUATIONS

24. AMPERE’S LAW

25. Reasons for the Extra Term u SYMMETRY u CONTINUITY

26. SYMMETRY u A time varying magnetic field produces an electric field. u A time varying electric field produces a magnetic field.

27. SYMMETRY

28. CONTINUITY

32. AMPERE’S LAW

34. ELECTROMAGNETIC WAVES

36. MAXWELL’S EQUATIONS