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8th Grade

Electromagnetic Radiation CW-HW Slides

2015-10-23 www.njctl.org

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Classwork #1: What is Electromagnetic Radiation

c = λf c = 300,000,000 m/s time (s) = distance (m)/ speed (m/s)

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1 What are some sources of electromagnetic radiation?

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2 What is meant by the term “medium”?

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3 Why can electromagnetic waves travel through a vacuum?

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4 What speed do all electromagnetic waves travel at in vacuum?

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5 Red light, a type of electromagnetic wave, has a wavelength of 0.0000078 meters, what is its frequency in Hz?

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6 Most kitchen microwaves operate at a frequency

• f 2,450 MHz or 2,450,000,000 Hz. What is the

wavelength of these microwaves?

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7 Alpha Centauri is the nearest star to Earth at 41,342,509,100,000,000 meters away. How long would it take a radio signal – a type of electromagnetic wave – from Alpha Centauri to reach Earth?

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8 TV channels 5 and 6 broadcast frequencies between 76 and 88 MHz. What is the wavelength

• f a 76 MHz frequency?

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Homework: What is Electromagnetic Radiation

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9 What do X-rays, light, microwaves, and radio waves all have in common?

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10 All electromagnetic waves travel at what speed in a vacuum?

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11 What is a vacuum?

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12 When electromagnetic waves travel through matter, what happens to their speed?

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13 Which of the following electromagnetic waves has the highest frequency: 1.0 m wavelength, 100 m wavelength, 0.001 m wavelength, or 1,0000 m wavelength?

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14 How does the frequency of an electromagnetic wave with a long wavelength compare to the frequency of an electromagnetic wave with a short wavelength?

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Classwork #2: The Electromagnetic Spectrum

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15 What does the term “spectrum” mean?

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16 What happens to the energy of a wave as the frequency of a wave increases?

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17 What happens to the energy of a wave as the wavelength of a wave increases?

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18 What form of electromagnetic wave has the highest energy?

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19 What form of electromagnetic wave has the lowest energy?

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20 Which color in the visible portion of the electromagnetic spectrum carries the most energy?

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21 Rank the following forms of electromagnetic radiation in order of increasing energy: Infrared Waves, Radio Waves, X-Rays

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22 Rank the following forms of electromagnetic radiation in order of increasing energy: Gamma Rays, Microwaves, Ultraviolet

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Homework: The Electromagnetic Spectrum

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23 In order for a radio to work, what two items are needed?

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24 What are 5 ways microwaves are used?

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25 What are the three major categories of light electromagnetic radiation?

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26 Describe characteristics/ uses of the three major categories identified in #25.

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27 Rank the following in order from longest to shortest wavelength: red light, infrared, ultraviolet, and violet light.

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28 What does the acronym ROYGBIV stand for and what is its purpose?

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29 How does the amplitude of a visible light wave relate to the light's brightness?

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30 What are the two highest energy types of electromagnetic radiation and what are they used for?

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Classwork #3: Light Interactions with Matter

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31 What is the imaginary line perpendicular to the surface of a material called?

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32 The angle between the incoming light and the line asked for in #31 is called what?

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33 What is the angle between the reflected light and the line in #31 called?

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34 What is the relationship between the two angles in #32 and #33?

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35 What is another term for the bending of light?

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36 In order for light to refract what two conditions must be met?

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37 Explain what causes light to refract as it goes from

• ne medium to another.

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38 If light enters a denser material from one that is less dense, how will the light behave?

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39 If light enters a less dense material from one that is denser, how will the light behave?

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Homework: Light Interactions with Matter

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40 Based on the diagram below, which substance is denser? How do you know

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41 What does the light ray B represent? How about ray C? Explain.

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42 When light enters a substance with a different density, what is the angle of reflection?

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43 How does the angle of refraction for light with a higher frequency compare to that of a lower frequency light?

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44 How does the angle of refraction compare for red and violet light passing through the same object? Explain.

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45 If a light passes from air, through glass, and back into air, how does the angle of refraction from glass to air compare to the angle of incidence from air to glass?

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Classwork: Examples of Light Interactions with Matter

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46 How is refraction and reflection involved in the formation of rainbows?

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47 What causes the white areas to show up on an x-ray image?

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48 Explain how digital cameras capture images.