Slide 1 / 147 Slide 2 / 147 8th Grade Electromagnetic Radiation 2015-10-23 www.njctl.org Slide 3 / 147 Slide 4 / 147 Table of Contents Click on the topic to go to that section What is Electromagnetic Radiation? · What is Electromagnetic Radiation? The Electromagnetic Spectrum · Interactions with Matter · Examples of Light Interactions with Matter · Return to Table of Contents Slide 5 / 147 Slide 6 / 147 Electromagnetic Radiation Electromagnetic Radiation We are constantly bombarded by electromagnetic radiation, most of which we cannot see. What do X-rays, light, microwaves, radio waves, and infrared have in common? Click in the box to see the answer. Note http://www.epa.gov/radtown/enter-radtown.html They are all types of electromagnetic radiation.
Slide 7 / 147 Slide 8 / 147 Electromagnetic Radiation Electromagnetic Radiation Radiation can be described as the movement of energy through space. Not all electromagnetic radiation we interact with is bad. When you cook food in a microwave, listen to music, see colors, or feel heat, you are experiencing electromagnetic radiation. There are many different sources of radiation that vary by intensity. The Sun, light bulbs, nuclear reactions, and radon gas, are all sources that produce electromagnetic radiation. We are constantly bombarded by electromagnetic radiation, How do you think electromagnetic radiation travels through space? most of which we cannot see. Slide 9 / 147 Slide 10 / 147 Electromagnetic Waves Electromagnetic Radiation Electromagnetic waves are produced by vibrating electric charges. One way electromagnetic radiation travels through space When an electric charge vibrates, its electric field changes, is as a wave. producing a changing magnetic field. The electric and magnetic field are perpendicular to each other. The changing magnetic field produces a changing electric field. Electromagnetic waves are The changing electric field produces a changing magnetic field. different from mechanical And so on and so on and so on...creating a transverse waves because they don't electromagnetic wave. need a medium to travel through. What's "waving" in an electromagnetic wave? Slide 11 / 147 Slide 12 / 147 How Electromagnetic Waves Travel Electromagnetic Wave Characteristics Electromagnetic waves have the same wave characteristics we studied last unit: Electromagnetic waves do not need a medium to travel through. wavelength (λ) measured in meters This means electromagnetic waves can travel through empty frequency (f) measured in Hz space as well as through mediums like air or water! speed (c) 300,000,000 meters/second Electromagnetic waves also do not lose energy as they travel. This Wavelength and frequency vary based on the type of is unlike mechanical transverse waves which lose some of their electromagnetic wave, but all electromagnetic waves travel energy to their medium. at the same speed in a vacuum. An electromagnetic wave continues to go straight and spread out What is a vacuum? until it collides with some form of matter, at which point the direction of travel will change. Hint: Not this!
Slide 13 / 147 Slide 14 / 147 Speed of Electromagnetic Radiation The Vacuum of Empty Space Scientists use the idea of constant speed ( c ) A vacuum is a space that is completely empty and contains no matter. A true vacuum does not actually exist because in a vacuum because it's useful for even nearly empty parts of the Universe contain some matter. calculations. c is also referred to as the speed of light. The closest thing to a vacuum that has been produced in a lab is a space that has one billionth of one billionth of the In theory, nothing can travel faster than the speed of light. In reality, electromagnetic standard pressure of the atmosphere! waves slow down when encountering any matter. If you could travel at the speed of light, you could go around Earth's equator 7.5 times in one second. Slide 15 / 147 Slide 15 (Answer) / 147 Wavelength of Electromagnetic Radiation Wavelength of Electromagnetic Radiation Different types of Different types of electromagnetic electromagnetic radiation have different radiation have different Answer wavelengths. wavelengths. Drag and drop the terms Drag and drop the terms into the correct place on into the correct place on the wave. the wave. [This object is a pull tab] wavelength crest trough wavelength crest trough Slide 16 / 147 Slide 17 / 147 Frequency of Electromagnetic Radiation Speed, Wavelength and Frequency All forms of electromagnetic radiation travel at the same speed when not in contact with matter. However, different forms of A wave's frequency or wavelength can be solved for using the electromagnetic radiation have different wavelengths, and therefore wave equation from last unit: must have different frequencies. There is an inverse relationship between Since all electromagnetic radiation travels at the speed of light, wavelength and frequency. v can be replaced with this value every time, represented by the letter c, which equals 300,000,000 m/s. What does this mean? Click in the box to see the answer. As one value goes up, the other goes down. For example, the longer the wavelength, the lower the frequency.
Slide 18 / 147 Slide 19 / 147 Speed, Wavelength and Frequency 1 If you could travel at the speed of electromagnetic waves in a vacuum, how long would it take you to travel from the surface of Earth to the Moon? We use the new wave equation to solve for the frequency or speed = c = 300,000,000 m/s wavelength of electromagnetic waves based on the equations below: distance between Earth and Moon = 356,400 km or 356,400,000 m or t = d/s Click here to watch a video that proves the speed of light by using chocolate and a microwave! Slide 19 (Answer) / 147 Slide 20 / 147 1 If you could travel at the speed of electromagnetic waves 2 The Sun is 149,600,000 km away from Earth. How many in a vacuum, how long would it take you to travel from the minutes ago did the radiation that is hitting you right now surface of Earth to the Moon? leave the Sun? speed = c = 300,000,000 m/s c = 300,000,000 m/s distance between Earth and Moon = 356,400 km or 356,400,000 m Answer 1.19 s t = d/s [This object is a pull tab] Slide 20 (Answer) / 147 Slide 21 / 147 3 Radio waves are electromagnetic waves with long 2 The Sun is 149,600,000 km away from Earth. How many wavelengths. If an AM radio wave's frequency is 540,000 minutes ago did the radiation that is hitting you right now Hz, what is its wavelength? Is it long enough to bounce leave the Sun? over the Empire State Building (381 m)? c = 300,000,000 m/s *Remember to convert c = 300,000,000 m/s 149,600,00 km to Answer 149,600,000,000 m. t = 498.67 sec or about 8 minutes [This object is a pull tab]
Slide 21 (Answer) / 147 Slide 22 / 147 3 Radio waves are electromagnetic waves with long 4 What is the frequency of a radio wave that has a wavelengths. If an AM radio wave's frequency is 540,000 wavelength of 1 cm (0.01 m)? Hz, what is its wavelength? Is it long enough to bounce over the Empire State Building (381 m)? c = 300,000,000 m/s Answer 556 m; Yes [This object is a pull tab] Slide 22 (Answer) / 147 Slide 23 / 147 4 What is the frequency of a radio wave that has a 5 An electromagnetic wave has a frequency of 1.5 GHz wavelength of 1 cm (0.01 m)? (1,500,000,000 Hz). What is the wavelength of the wave? (1 GHz = 1,000,000,000 Hz) Answer 3.0 x 10 10 Hz [This object is a pull tab] Slide 23 (Answer) / 147 Slide 24 / 147 5 An electromagnetic wave has a frequency of 1.5 GHz 6 Red light has a frequency of 4.6 x 10 14 Hz (1,500,000,000 Hz). What is the wavelength of the (460,000,000,000,000 Hz). What is the wavelength of wave? (1 GHz = 1,000,000,000 Hz) red light? Answer 0.2 m [This object is a pull tab]
Slide 24 (Answer) / 147 Slide 25 / 147 6 Red light has a frequency of 4.6 x 10 14 Hz 7 Which of the following electromagnetic wavelengths (460,000,000,000,000 Hz). What is the wavelength of would have the highest frequency? red light? A 100 m B 10 m C 1 m Answer 6.5 x 10 -7 Hz D 0.1 m (0.00000065 Hz) [This object is a pull tab] Slide 25 (Answer) / 147 Slide 26 / 147 7 Which of the following electromagnetic wavelengths 8 Which of the following frequencies would have the would have the highest frequency? shortest wavelength? A 100 m A 1000 Hz B 10 m B 100 Hz Answer C 1 m C 10 Hz D D 0.1 m D 1 Hz [This object is a pull tab] Slide 26 (Answer) / 147 Slide 27 / 147 8 Which of the following frequencies would have the shortest wavelength? A 1000 Hz The Electromagnetic Spectrum B 100 Hz Answer A C 10 Hz D 1 Hz [This object is a pull tab] Return to Table of Contents
Recommend
More recommend
