1. November 18, 2013

2. Electromagnetic Radiation

3. Objectives At the end of class, you will be able to: List the forms of electromagnetic radiation Find wavelength or frequency of electromagnetic radiation

4. Waves and Particles Particles are solid matter Waves are movement in matter, like an ocean wave or a wave at a football game

5. Electromagnetic Radiation Energy that travels through space as a wave EXAMPLES: Gamma rays X-rays Ultraviolet rays Visible light Infrared Microwaves Radiowaves Electromagnetic spectrum

6. In a vacuum all electromagnetic radiation travels at the speed of light. This speed is c = 3.0 × 10 8 m/s

8. Wavelength Symbol: λ (lambda) Units: m (meter) Distance between corresponding points on a wave

9. Frequency Symbol: ν (nu) Units: s -1, Hz, 1/s Number of waves that pass a point per second

10. Each form of light has different wavelength and frequency, but they all have the SAME SPEED

12. As wavelength ______________, frequency _______________. As wavelength ______________, frequency ________________. increases decreases increases

13. The big equation for EM radiation: c = λν

14. PRACTICE: 1. What is the wavelength of electromagnetic radiation with a frequency of 2.0 × 10 15 Hz? Where is this in the electromagnetic spectrum? If it is visible light, what color is the light? Use formula: c = λν Identify known information: c = 3.0 x 10 8 m/s ν = 2.0 × 10 15 Hz Plug known information into formula: 3.0 x 10 8 m/s = λ( 2.0 × 10 15 Hz) Solve for λ λ = (3.0 x 10 8 m/s)/ ( 2.0 × 10 15 Hz) λ = 1.5 × 10 -7 m

15. Ultraviolet light

16. PRACTICE: 2. What is the frequency of light with a wavelength of 4.5 × 10 -7 m? Where is this in the electromagnetic spectrum? If it is visible light, what color is the light? Use formula: c = λν Identify known information: c = 3.0 x 10 8 m/s λ = 4.5 × 10 -7 m Plug known information into formula: 3.0 x 10 8 m/s = (4.5 × 10 -7 m) ν Solve for ν ν = (3.0 x 10 8 m/s)/ ( 4.5 × 10 -7 m) ν = 6.67 × 10 14 Hz

17. Visible light – Blue

18. PRACTICE: 3. What is the wavelength of electromagnetic radiation with a frequency of 5.85 × 10 18 Hz? Where is this in the electromagnetic spectrum? If it is visible light, what color is the light? Use formula: c = λν Identify known information: c= 3.0 x 10 8 m/sv = 5.85 x 10 18 Hz Plug known information into formula: 3.0 x 10 8 m/s = λ (5.85 x 10 18 s -1 ) Solve for ν ν = (3.0 x 10 8 m/s)/(5.85 x 10 18 s -1 ) = ν = 5.13 x 10 -11 m

19. Gamma Rays (or X-rays) – The wavelengths overlap sometimes

20. PRACTICE: 4. What is the frequency of light with a wavelength of 64 cm? Where is this in the electromagnetic spectrum? If it is visible light, what color is the light? Hint: make sure all variables are in units of m! 64 cm | 1m = 0.64 m 100 cm

21. PRACTICE: 4. What is the frequency of light with a wavelength of 0.64 m? Where is this in the electromagnetic spectrum? If it is visible light, what color is the light? Use formula: c = λν Identify known information: c= 3.0 x 10 8 m/s λ = 0.64 m Plug known information into formula: 3.0 x 10 8 m/s = (0.64m) ν Solve for ν ν = ( 3.0 x 10 8 m/s)/(0.64 m) = ν = 4.69 x 10 8 Hz

22. Radio Waves

23. Check: What is wavelength? What is the unit for wavelength? What is frequency? What is the unit for frequency? How can you find one if you know the other?