2. AIM: What is light?

6. Recognize that light is a form of energy. Recognize the shape of a light wave Recognize the type of wave that light is AIM: What is Light?

7. Electromagnetic Energy, photon, ray, speed, wavelength, amplitude, frequency AIM: What is Light?

8. DEMO: How does light travel? If we look at a light through a straw, what do we see? If we bend the straw, can we still see the light? Why not? Light travels in a straight line!

9. What is a ray of light? Light is actually made of up millions of rays of light all around each other. Each separate ray of light traveling in a straight line

10. Light is a form of electromagnetic energy. Light travels as photons

11. Photons are tiny bundles of energy. Photons can not be seen individually. A beam of light is made up of a stream of many photons.

12. What are mechanical waves? Waves which need a medium Since light is an electromagnetic wave, does it need a medium? NO!

13. Will light will travel in a vacuum. YES !

14. Light actually travels similar to a transverse wave. DRAW an Example of a TRANSVERSE WAVE. Label the crest, trough, amplitude and wavelength

15. AIM: What is light? Amplitude Brighter light have greater amplitudes !

16. What is FREQUENCY ?

17. The number of complete waves that pass a certain point in a a given amount of time. (Usually in waves per second) AIM: What is light?

18. A complete wave is measured as “from one crest (or trough) to the next” Crest

19. If these dotted lines represent a 1 second interval, What would be the frequency of this wave?.

20. If these dotted lines represent a 3 second interval, What would be the frequency of this wave?.

21. WHAT UNIT IS FREQUENCY MEASURED IN ? Definition of Hertz: unit used to measure frequency a measure of the number of complete waves per second AIM: What are features of waves?

22. What does 15,000 hertz mean? AIM: What are features of waves?

23. The speed of a wave = (frequency) x (wavelength) AIM: What are features of waves?

24. Speed = frequency x wavelength The speed how many meters it travels per second The hertz (frequency) is a measure of complete cycles each second

25. What is the speed of light in a vacuum? 300,000 km/sec So, if a given light wave had a wavelength of 1000 meters, what would be its frequency? S = Hz x wl 300,000 = ? X 1000

26. So, if a given light wave had a wavelength of 100 meters, what would be its frequency? S = Hz x WL 300,000 = ? X 100 3000 = Hz

27. So, if a given light wave had a wavelength of.1 meters, what would be its frequency? S = Hz x WL 300,000 = ? X.1 3,000,000 Hz = ?

28. So, if a given light wave had a wavelength of.01 meters, what would be its frequency? S = Hz x WL 300,000 = ? X.01 30,000,000 Hz = ? This is more of a Typical Frequency for Light Rays!

29. So, as the wavelength decreases What happens to the frequency? Frequency Increases What happens when frequency decreases? Wavelength increases

30. Light travels as rays Light travels in straight lines Light is an EM wave Light does not need a medium Light travels as photons

31. Class Activity: W/S Concepts 9-1, 9-2 AIM: What is light?

32. Homework: INTERNET QUESTIONS