1. Sound and LightSection 2 EQ: How can I explain the characteristics of waves?

2. Sound and LightSection 2 Waves and Particles How do scientific models describe light?

3. Sound and LightSection 2 16-2-1 Waves and Particles Dual nature of light: Light must be thought of as both waves and as streams of particles because neither concept alone can explain all of it’s properties.

4. Sound and LightSection 2 16-2-2 Waves and Particles, continued Light does not require a medium and consists of transverse electromagnetic waves with electric and magnetic fields.

5. Sound and LightSection 2 16-2-3 Waves and Particles, continued The wave model of light explains how light waves interfere with one another why light waves may reflect why light waves refract why light waves diffract

6. Sound and LightSection 2 16-2-4 Waves and Particles, continued The particles of light are massless photons that are packets or quanta of energy with specific frequencies.

7. Sound and LightSection 2 16-2-5 Waves and Particles, continued The particle model of light explains –The photoelectric effect when photons cause electrons to be emitted from metals –Reflection –Refraction

8. Sound and LightSection 2 16-2-6 Waves and Particles, continued The amount of energy in a photon is proportional to the frequency of the corresponding electromagnetic wave.

9. Sound and LightSection 2 Waves and Particles, continued

10. Sound and LightSection 2 Waves and Particles, continued The speed of light depends on the medium.

11. Sound and LightSection 2 16-2-7 Waves and Particles, continued Intensity (brightness): depends on the number of photons per second, or power, that pass through a certain area of space.

12. Sound and LightSection 2 The Electromagnetic Spectrum What does the electromagnetic spectrum consist of?

13. Sound and LightSection 2 16-2-8 The Electromagnetic Spectrum The electromagnetic spectrum consists of light at all possible energies, frequencies, and wavelengths.

14. Sound and LightSection 2 16-2-9 The Electromagnetic Spectrum The visible spectrum is only a very small part of the electromagnetic spectrum.

15. Sound and LightSection 2 16-2-10 The Electromagnetic Spectrum Each part of the electromagnetic spectrum has unique properties.

16. Sound and LightSection 2 16-2-11 The Electromagnetic Spectrum, continued Radio waves have wavelengths that range from tenths of a meter to thousands of meters.

17. Sound and LightSection 2 16-2-12 The Electromagnetic Spectrum, continued Microwaves are used in cooking and communication and have wavelengths in the range of centimeters.

18. Sound and LightSection 2 16-2-13 The Electromagnetic Spectrum, continued Infrared light can be felt as warmth and are slightly longer than red visible light.

19. Sound and LightSection 2 16-2-14 The Electromagnetic Spectrum, continued Sunlight contains ultraviolet light. The invisible light that lies just beyond violet light falls into the ultraviolet (UV) portion of the spectrum.

20. Sound and LightSection 2 16-2-15 The Electromagnetic Spectrum, continued X rays and gamma rays are used in medicine. –X rays have wavelengths less than 10 –8 m.

21. Sound and LightSection 2 16-2-16 The Electromagnetic Spectrum, continued –Gamma rays are the electromagnetic waves with the highest energy. They have wavelengths shorter than 10 –10 m.