Topic : Waves Aim : Describe the electromagnetic spectrum. Do Now : next slide

1. Topic: Waves Aim: Describe the electromagnetic spectrum. Do Now: next slide HW: CL Energy due Monday CL Waves due Thursday

2. Any substance through which a wave can travel is called a • solid • vacuum • medium • liquid

3. Waves transfer • energy • matter • particles • heat

4. Which of the following is the best example of a wave? • A stone rolling downhill • A vehicle moving on a bumpy road • A string vibrating on a guitar • A grasshopper jumping up and down

5. Which of the following statements applies to longitudinal waves? • The motion of the medium is random. • The motion of the medium is in a circular pattern. • The motion of the medium is parallel to the motion of the wave. • The motion of the medium is perpendicular to the motion of the wave.

6. Sound reaches our ears because sound makes particles • heat up. • slow down. • cool down. • vibrate.

7. The distance between the Earth and the moon was determined by measuring the time it took for light waves from the Earth to travel to the moon and back. Why was it not possible to use sound waves for this experiment? • Sound waves must move through a substance. • Sound waves change frequency on the return to earth. • Sound waves move too slowly for this technique to be accurate. • Sound waves move more slowly in the Earth’s atmosphere than in space.

8. A large spring is stretched horizontally between 2 people. One person wiggles the spring up and down at one end. The up-and-down vibration then moves along the spring on to the other person. Which of the following type of wave is created in the spring? • pressure wave • longitudinal wave • transverse wave • nonmechanical wave

9. Identify the kind of wave represented in each diagram. Support your answer. longitudinal wave transverse wave

10. Which wave has the greatest amplitude? • Which wave has the greater wavelength? • Which wave has the greater frequency?

11. Electromagnetic wave Can travel through a vacuum (no medium needed) Consists of an electric field and a magnetic field

13. Radiant Energy Energy transferred by an EW

14. Speed of an EW In a vacuum = 300 million m/s Speed of light

16. In matter = speed depends on medium • Slow in solids, fastest in gases

17. Light is a type of electromagnetic wave. In matter, it’s speed depends on the medium it travels though.

18. Electromagnetic Spectrum EW in order of wavelength & frequency

19. Low frequency = long wavelength High frequency = Short wavelength

21. High frequency = a lot of energy

22. Parts of the Electromagnetic Spectrum

23. Radio Waves Longest wavelength Lowest frequency

24. Used for radio, TV, radar, MRI’s

26. Microwaves Cell phones, satellite signals, microwave ovens

29. Infrared Waves Felt as heat Ex: Remote controls emit infrared waves to control TV

30. Computers - to read CD-ROMs.

31. Thermal imaging

33. Visible Light Only part you can see Red, orange, yellow, green, blue, indigo, violet (ROY G BIV)

34. Red = longest wavelength • Violet = shortest wavelength

35. ROYGBIV

38. Ultraviolet Rays Can enter skin cells Too much  sunburn  skin cancer

40. Some is needed  lets skin make Vitamin D (healthy bones & teeth)

41. Kills bacteria

42. Make some materials fluorescent • Fluorescent powder  show fingerprints

43. Ozone layer absorbs most of sun’s harmful UV waves

45. X-rays High energy Images of internal organs, bones, teeth

46. Airport screening devices

49. Gamma Rays Highest energy and frequency Shortest wavelength

50. Produced during nuclear reactions (in nucleus of atoms)