2. Chapter 22 Electromagnetic Waves 22-1Changing Electric Fields Produce Magnetic Fields; Maxwell Equations James Clerk Maxwell (1831-1879)… showed that all electric and magnetic phenomena could be described using only four equations…these equations are known as Maxwell’s equations…( Described below.) 1. Gauss’s Law that relates electric fields to its sources. 2. A similar law that relates magnetic fields to its sources. 3. An electric field is produced by a changing magnetic field. 4. A magnetic field is produced by an elecrtic current, or by a changing electric field.

3. 22-2 Maxwell’s 4 th Equation; Displacement Current See diagrams page 662. Ordinary current is called conduction current. Displacement current was Maxwell’s term to describe the loss of current that caused an electric field. The equation (22-1) embodies Maxwell’s idea that a magnetic field can be caused not only bay a normal electric current, but also by a changing electric field or changing electric flux.

4. 22-3 Production of Electromagnetic Waves See diagrams pg. 664 and 665. See equations page 666

5. 22-5 Light as an Electromagnetic Wave and the Electromagnetic Spectrum f =c c= 3.00 x 10 8 m/s Electromagnetic spectrum (page 670) See Example 22-1 p671 See Example 22-2 p671

6. 22-6 Measuring the Speed of Light Albert A. Michelson (1852-1931) See page 672

7. HOMEWORK P680 1-2,7-9, 10-17 due BOP Thursday