1. Electromagnetic Spectrum Electromagnetic Spectrum (EM Spectrum) is the entire range of light radiation from gamma rays to radio waves.

2. James Clerk Maxwell made a unified theory to describe electricity and magnetism in 4 equations. He predicted that EM waves exist and predicted the speed of light. Electromagnetism : phenomena caused by electricity and magnetism together. Electromagnetic Waves : Electric and magnetic fields work together to create traveling waves.

3. Electromagnetic Spectrum Gamma Rays10 19 Hz to ∞ X-Rays10 17 Hz to 10 19 Hz Ultraviolet7.5x10 14 Hz to 10 17 Hz Visible Light4x10 14 Hz to 7.5 x 10 14 Hz Infrared10 11 Hz to 4x10 14 Hz Microwaves10 8 Hz to 10 12 Hz Radio Waves10 2 Hz to 10 8 Hz

4. Speed of Light “c” Romer (1644-1710: Danish) measured orbital period of Io around Jupiter and noted differences depending on where Earth was located. Deduced a speed of light. Fizeau (1819-1896: French) first measured speed of light with mirrors and a notched rotating wheel. Michelson (1852-1931:American) measured more accurately with an 8 sided rotating mirror and a stationary mirror set 35 km apart on Mt. Wilson and Mt. Baldy in Ca. (pg 622 in text)

5. Speed of Light “c” Velocity = Frequency (s -1 ) * Wavelength (m) Speed of Light c = 299,792,458 m/s c ≈ 3.0 x 10 8m/s c = ƒλ

6. Calculation Calculate λ of the spectrum… Electromagnetic Spectrum Gamma Rays10 19 Hz to ∞ X-Rays10 17 Hz to 10 19 Hz Ultraviolet7.5x10 14 Hz to 10 17 Hz Visible Light4x10 14 Hz to 7.5 x 10 14 Hz Infrared10 11 Hz to 4x10 14 Hz Microwaves10 8 Hz to 10 12 Hz Radio Waves10 2 Hz to 10 8 Hz

7. How does that work???? The Radio AM Amplitude Modulation FM Frequency Modulation

8. How does that work???? Sound pressure waves (mechanical) → microphone → audio frequency (electrical) → mixed with radio frequency (carrier) → amplified → transmitted. (Text pg 626 fig 22-12)

9. Calculation Page 630: Problems 11, 13 & 27