1. APHY201 10/24/2015 1 22.1 Maxwell’s Equations   1865 – James Maxwell unifies electricity and magnetism and shows that their fields move through space as waves.   He calculated that the EM waves travel at the speed of light so they must be a type of light.   1887 – Heinrich Hertz generates and detect EM waves for the first time

2. APHY201 10/24/2015 2 22.2 Production of Electromagnetic Waves   Energy is stored in E and B   Magnitude of E and B are   At large distances, the waves are planar or flat.

3. APHY201 10/24/2015 3 22.2 Production of Electromagnetic Waves   EM waves are transverse EM waves Amplitude is perpendicular to wave motion   EM waves travel at c = E/B = 3 x 10 8 m/s

4. APHY201 10/24/2015 4 22.3 Light and the Electromagnetic Spectrum   Speed = Frequency * Wavelength c = f λ

5. APHY201 10/24/2015 5 22.3 Light and the Electromagnetic Spectrum 5 X-ray Visible PolarizedRadio

6. APHY201 10/24/2015 6 22.6 Momentum Transfer and Radiation Pressure   Remember that   Maxwell showed that where a = 1 to 2   Since and then

7. APHY201 10/24/2015 7 22.6 Momentum Transfer and Radiation Pressure

8. APHY201 10/24/2015 8 22.7 Wireless Transmission   Radio and wireless telegraph (1890’s)   The FCC and broadcast “bands”

9. APHY201 10/24/2015 9 22.7 Wireless Transmission

10. APHY201 10/24/2015 10 22.7 Wireless Transmission

11. APHY201 10/24/2015 11 22.7 Wireless Transmission