1. Day 3 Pick up handouts on the front table!

2. 1. Identify different items at home that produce waves. 2. What is the unit for frequency? Agenda Electromagnetic waves.

3. Q1: W HAT IS AN EXAMPLE OF A UNIFORMITY OF PROCESS ? A. human destruction B. pollution C. erosion D. craters SC8.4.4.a DOK 1

4. Q2: H OW DOES LIGHT DETERMINE THE COLOR OF AN OPAQUE OBJECT ? A. diffraction B. reflection C. refraction D. transmission SC8.2.3.d DOK 1

5. A teacher has 200 books inthelibrary and 25% of these books are about math. Science books represent 30% of the remaining books. How many of each book does the teacher have?

6. Greek /LatinMeaningExample camp-field -undwave electro-electricity photo-light kine-motion

7. I will know the definition of an electromagnetic wave. I will know how an electromagnetic wave travels. I will be able to mathematically solve story problems involving electromagnetic waves.

8. 1. Identify different items at home that produce waves. Answer: microwave produces microwave, remote control produces infrared wave, etc. 2. What is the unit for frequency? Hz

9. A1: W HAT IS AN EXAMPLE OF A UNIFORMITY OF PROCESS ? A. human destruction This is not an event caused by an earth process. B. pollution This is not an event caused by an earth process. C. erosion This is an earth process. D. craters While these happen on the earth, they are not an earth process. SC8.4.4.a DOK 1

10. A2: H OW DOES LIGHT DETERMINE THE COLOR OF AN OPAQUE OBJECT ? A. diffraction Diffraction is the slight bending of light as it passes around the edge of an object and can cause a rainbow effect. For example, on a CD or DVD. B. reflection The color of an opaque object is determined by the wavelength of the light that it reflects. C. refraction Refraction is the change in direction of a wave due to a change in its speed. For example, light will refract as it enters or leaves glass. D. transmission Transmission refers to percentage of visible light that passes through a substance. For example, tinting a car window will cut down on the amount of visible light transmitted. SC8.2.3.d DOK 1

11. Answer: Number of math book = 25% of 200 = 50 Number of science book = 30% of 150 = 45 A teacher has 200 books in his library and 25% of these books are about math. Science books represent 30% of the remaining books. How many of each book does the teacher have?

12. The waves that carry a person’s cell phone conversation are not visible. Fun fact:

13. Electromagnetic waves are transverse waves consisting of changing electric fields and changing magnetic fields.

14. FUN FACT S OMETIMES THE EARTH ’ S MAGNETIC FIELD COMPLETELY FLIPS. T HE NORTH AND THE SOUTH POLES SWAP PLACES. S UCH REVERSALS, RECORDED IN THE MAGNETISM OF ANCIENT ROCKS, ARE UNPREDICTABLE. T HEY COME AT IRREGULAR INTERVALS AVERAGING ABOUT 300,000 YEARS ; THE LAST ONE WAS 780,000 YEARS AGO. A RE WE OVERDUE FOR ANOTHER ? N O ONE KNOWS. http://science.nasa.gov/science-news/science-at-nasa/2003/29dec_magneticfield/

15. Electromagnetic waves are produced when an electric charge vibrates or accelerates. Picture of accelerated electrons

16. How are electromagnetic waves different from mechanical waves?

17. How are electromagnetic waves different from mechanical waves? -- ANSWER Electromagnetic waves can travel through a vacuum as well as through matter but mechanical waves can only travel through a medium. Most of space is a vacuum Betelgeuse

18. The Speed of Electromagnetic Waves ALL electromagnetic waves travel at the same rate: 3.0×10 8 m/s

19. T URN TO YOUR PARTNER D ISCUSS WITH A PARTNER THEIR IDEAS OF DIFFERENT TYPES OF WAVES THAT COULD BE AN ELECTROMAGNETIC WAVE.

20. T URN TO A PARTNER P OSSIBLE A NSWERS : Radio Waves X-rays SOUND IS NOT AN ELECTROMAGNETIC WAVE Cell phones TV

21. A LL THESE WAVES HAVE ONE THING IN COMMON – THEY ARE ALL RADIATION ! Radio Waves X-rays Cell phones TV

22. The electromagnetic spectrum is just a name that scientists give a bunch of types of radiation!

23. Electromagnetic waves vary in wavelength and frequency.

24. S MALL GROUP – W HICH WAVE OF THE ELECTROMAGNETIC SPECTRUM HAS THE SHORTEST WAVELENGTH ? W HAT DO YOU NOTICE ABOUT THE FREQUENCY ?

25. S MALL GROUP – W HICH WAVE OF THE ELECTROMAGNETIC SPECTRUM HAS THE SHORTEST WAVELENGTH ? W HAT DO YOU NOTICE ABOUT THE FREQUENCY ? – ANSWER GAMMA RAYS HAVE THE SHORTEST WAVELENGTH AND THE HIGHEST FREQUENCY

26. Small group: Decide which relationship (linear, inverse, or inverse squared) is involved when the velocity stays constant (3 x 10 8 m/s) and the ray has a short wavelength and a long frequency. v f λ

27. Small group: answer decide which relationship is involved when the velocity stays constant (3 x 10 8 m/s) and the ray has a short wavelength and a long frequency. Velocity = λ × f Constant Inverse relationship

28. FUN FACTS #1 Radio Waves How are radio waves used? Radio waves are used in radio and television technologies, as well as in microwave ovens and radar. Wavelengths range from 1 millimeter to as much as thousands of kilometers or longer.

29. The shortest-wavelength radio waves are called microwaves. Microwave wavelengths are from about 1 m to about 1 mm. Frequencies vary from about 300 MHz to about 300,000 MHz. Microwaves cook and reheat food. Microwaves also carry cell phone conversations. The process works much like a radio broadcast. FUN FACTS #2 MICROWAVES

30. FUN FACTS #3 Infrared Rays Infrared rays are used as a source of heat and to discover areas of heat differences. Infrared wavelengths vary from about 1 millimeter to about 750 nanometers (10 –9 meter). Your skin senses infrared radiation as warmth.

31. Turn to a partner and discuss how infrared rays are used.

32. Search-and-rescue teams use infrared cameras to locate people who are trapped during disasters. Turn to a partner and discuss how infrared rays are used. – possible answers Restaurants use infrared lamps to keep foods warm.

33. The visible part of the electromagnetic spectrum is light that the human eye can see. Each wavelength in the visible spectrum corresponds to a specific frequency and has a particular color. FUN FACTS #4 Visible Light

34. FUN FACT #5 Ultraviolet Rays Ultraviolet rays have applications in health and medicine, and in agriculture.

35. FUN FACTS #6 X-Rays X-rays are used in medicine, industry, and transportation to make pictures of the inside of solid objects. X-rays have very short wavelengths, from about 12 nm to about 0.005 nm.

36. Your teeth and bones absorb X-rays. X-ray photographs show softer tissue as dark, highly exposed areas. Bones and teeth appear white. The lids on aluminum cans are sometimes inspected with X-rays to make sure they are sealed properly. X-rays can be used to identify the contents of entire truck trailers. FUN FACTS #7 X-Rays

37. Airport security screeners use X- rays to search baggage for potentially dangerous objects. FUN FACT #8 X-Rays

38. FUN FACT #9 Gamma Rays Gamma rays are used in the medical field to kill cancer cells and make pictures of the brain, and in industrial situations as an inspection tool.

39. Gamma rays have the shortest wavelengths in the electromagnetic spectrum, about 0.005 nm or less. FUN FACT #10 Gamma Rays

40. Gamma rays are used in radiation therapy to kill cancer cells without harming nearby healthy cells. Pipelines are checked with machines that travel on the inside of a pipe, taking gamma ray pictures along the entire length. FUN FACT #11 Gamma Rays

41. They have the highest frequencies, the most energy, and the greatest penetrating ability of all the electromagnetic waves. Gamma Rays

42. Calculating Wave Speed A radio station broadcasts a radio wave with a wavelength of 3.0 meters. What is the frequency of the wave? Small Group

43. Calculating Wave Speed A radio station broadcasts a radio wave with a wavelength of 3.0 meters. What is the frequency of the wave? Givens: 3 m = λ Know: the speed of a radio wave 3 x 10 8 m/s Unknown: f Equation: v = λf Rearranged: f = v ÷ λ Plug in numbers: f = (3 x 10 8 m/s) ÷ 3 m Answer: f = 1 x 10 8 m/s Small Group-- answer

44. Is your answer reasonable? Small Group: Check that the product of wavelength and frequency gives a speed of 3.0 x 10 8 m/s. Yes, my answer is reasonable!

45. The radio waves of a particular AM radio station vibrate 680,000 times per second. What is the wavelength of the wave? Small Group Practice #2

46. The radio waves of a particular AM radio station vibrate 680,000 times per second. What is the wavelength of the wave? What do you think 680,000 times per second means? 680,000 Hz (Hz = 1/s) Givens: 680,000 Hz = f Know: the speed of a radio wave 3 x 10 8 m/s Unknown: λ Equation: v = λf Rearranged: λ = v ÷ f Plug in numbers: λ = (3 x 10 8 m/s) ÷ 680,000 Hz Answer: f = 441 m Small Group Practice #2 -- answers

47. A global positioning satellite transmits a radio wave with a wavelength of 19 cm. What is the frequency of the radio wave? ( Hint: Convert the wavelength to meters before calculating the frequency.) Individual Practice

48. A global positioning satellite transmits a radio wave with a wavelength of 19 cm. What is the frequency of the radio wave? ( Hint: Convert the wavelength to meters before calculating the frequency.) Givens: 19 cm = λ (÷100 λ = 0.19 m) Know: the speed of a radio wave 3 x 10 8 m/s Unknown: f Equation: v = λf Rearranged: f = v ÷ λ Plug in numbers: f = (3 x 10 8 m/s) ÷ 0.19 m Answer: f = 1.58 x 10 9 m/s Individual Practice -- answer

49. 1. Do page 527 Understanding Concepts answer questions # 11 - #15 2. Complete the Electromagnetic worksheet

50. E XIT Q UESTION -- D AY 3 Name 2 types of radiation on the electromagnetic spectrum and explain how they are used.

51. S UMMARY WRITING -- D AY 3 -- ANSWER Name 2 types of radiation on the electromagnetic spectrum and explain how they are used. Answers: Infrared rays – heat lamps in restaurants Gamma rays – to kill cancer cells Visible light – to read a book by X-rays – to see into my luggage at the airport