COURTESY OF PATRICK RONEY, ALIREZA SHAHSAFI AND MIKHAIL KATS February 1, 2020 Coating Provides Infrared Camouflage February 1, 2020 Coating Provides Infrared Camouflage About this Guide This Guide, based on the Science News article “Coating provides infrared camouflage,” asks students to explore the physics and potential technological applications of a material, discuss the various types of electromagnetic radiation, analyze infrared images and research how infrared imaging is used across a range of fields. This Guide includes: Article-based Comprehension Q&A — These questions, based on the Science News article “Coating provides infrared camouflage,” Readability: 12.7, ask students to explore the physics and potential technological applications of a material. Related standards include NGSS-DCI: HS-PS4; HS-PS3; HS-PS2; HS-ETS1. Student Comprehension Worksheet — These questions are formatted so it’s easy to print them out as a worksheet. Cross-curricular Discussion Q&A — Students will watch a NASA video about the electromagnetic spectrum to learn about properties of the various types of radiation. Then, students will explore and discuss technologies that use specific types of electromagnetic radiation. Related standards include NGSS- DCI: HS-PS4; HS-PS3; HS-PS2. Student Discussion Worksheet — These questions are formatted so it’s easy to print them out as a worksheet. Activity: Seeing in Infrared Summary: In this activity, students will analyze infrared images and then explore how infrared imaging is used across a range of fields of work. Skills include researching, evaluating, synthesizing and presenting information. Related standards include NGSS-DCI: HS-PS4; HS-PS3; HS-ETS1. Approximate class time: 1 class period to complete the discussion, research, presentations and debriefing as a class. February 1, 2020 Coating Provides Infrared Camouflage Article-based Comprehension, Q&A Directions for teachers: After your students read “Coating provides infrared camouflage,” ask them to answer the following questions. 1. How do infrared cameras work? Infrared cameras measure the amount of thermal radiation an object emits within the infrared region. The measurements are used to estimate the object’s temperature. 2. What is the relationship between an object’s temperature and the brightness of the thermal radiation it emits? What do physicists call this relationship? The hotter an object gets, the brighter its thermal radiation. This relationship is called the Stefan- Boltzmann law. 3. Name one way you can see this relationship in everyday life? When you turn on an electric stove, the heating coils glow brighter. 4. In what way does samarium nickel oxide appear to defy this relationship? When samarium nickel oxide is viewed by an infrared camera in certain wavelengths of infrared light, the material does not get brighter as its temperature increases. 5. What properties of the material explain this defiant behavior? At the temperatures described, the material switches from an insulator to a metal and its tendency to emit thermal radiation decreases. This decrease in emissivity counteracts the increase in brightness from the Stefan-Boltzmann law. 6. How did scientists apply samarium nickel oxide? What did they apply it to and what data did they collect? Scientists made a thin coating of samarium nickel oxide and used it to coat samples of sapphire. The scientists imaged heated samples with infrared cameras to see how brightly the samples glowed. 7. Why does the author describe the coating as a potential “camouflage”? Camouflage is a disguise that allows people or objects to hide. The material’s ability to maintain a constant brightness despite increasing temperature could be used to hide people or objects from infrared cameras, which image things based on the thermal radiation they emit. 8. Describe two limitations of using samarium nickel oxide as a camouflage. The temperature range in which the material’s brightness stays mostly constant is from 105° degrees Celsius to 135° Celsius — too high to hide people from detection by infrared cameras. Plus, the camouflage effect applies only at certain infrared wavelengths; cameras looking at different wavelengths would detect the change in brightness. 9. How does applied physicist Mikhail Kats plan to overcome one of the limitations? Kats suggests testing alloys of samarium nickel oxide. These materials may have different properties and so show the camouflage effect at lower temperatures. February 1, 2020 Coating Provides Infrared Camouflage Student Comprehension Worksheet Directions: After reading “Coating provides infrared camouflage,” answer the following questions. 1. How do infrared cameras work? 2. What is the relationship between an object’s temperature and the brightness of the thermal radiation it emits? What do physicists call this relationship? 3. Name one way you can see this relationship in everyday life? 4. In what way does samarium nickel oxide appear to defy this relationship? 5. What properties of the material explain this defiant behavior? 6. How did scientists apply samarium nickel oxide? What did they apply it to and what data did they collect? 7. Why does the author describe the coating as a potential “camouflage”? 8. Describe two limitations of using samarium nickel oxide as a camouflage. 9. How does applied physicist Mikhail Kats plan to overcome one of the limitations? February 1, 2020 Coating Provides Infrared Camouflage Cross-curricular Discussion, Q&A Directions for teachers: Use this exercise to introduce or review the electromagnetic spectrum with your class. Begin by showing the NASA video “Introduction to the Electromagnetic Spectrum.” Students should work with a partner through the prompts in “Properties of electromagnetic radiation.” Example answers are given. Then, students should choose a specific type of electromagnetic radiation to explore and research a technology that uses their chosen type. They can use the prompts in “Applications of technology using electromagnetic radiation” to prepare and give a brief presentation to their classmates. Directions for students: Properties of electromagnetic radiation Watch NASA’s “Introduction to the Electromagnetic Spectrum,” and answer the following prompts with a partner. Make sure you discuss the relationships between properties of electromagnetic radiation with your partner. Use additional resources if necessary. For instance, you could look up a diagram of the spectrum, such as this one provided by NASA. 1. Define the following terms: Electromagnetic radiation (make sure to include the name of each type): Waves with electrical and magnetic properties that carry energy from one place to another. Classified by wavelength, the types of electromagnetic radiation are gamma rays, X-rays, ultraviolet, visible light, infrared, microwaves and radio waves. Wavelength (and an appropriate unit used to measure it): The distance between two consecutive crests or toughs of a wave, typically measured in meters (m). Frequency (and an appropriate unit used to measure it): The number of crests that pass through a certain point in one second, typically measured in Hertz (Hz) or waves per second. The speed of light (and an appropriate unit used to measure it): The speed at which electromagnetic waves travel in a vacuum. The speed of light is typically measured in meters per second, and is equal to 3.0 x 108 m/s for all types of electromagnetic radiation. 2. Are the wavelength and frequency of electromagnetic waves directly or inversely related? Explain. Wavelength and frequency are inversely related. As the wavelength gets longer, the frequency gets smaller — fewer waves will pass through a certain point in a second — and vice versa. 3. Are the frequency and energy of electromagnetic waves directly or inversely related? Energy and frequency are directly related. As the energy increases, so does frequency — more waves will pass through a certain point in a second. As the energy decreases, fewer waves will pass through a certain point in a second. 4. Based on your answers to questions No. 2 and No. 3, what is the relationship between electromagnetic waves’ wavelength and energy? Since energy and frequency are directly related, and frequency and wavelength are inversely related, wavelength and energy must be inversely related. As a wave’s energy grows, its wavelength gets shorter, and vice versa. 5. To better understand how different types of electromagnetic radiation relate to each other, rank gamma rays, infrared, ultraviolet and radio waves in order of increasing: Wavelength Gamma rays, ultraviolet waves, infrared waves, radio waves Frequency Radio waves, infrared waves, ultraviolet waves, gamma rays Energy Radio waves, infrared waves, ultraviolet waves, gamma rays 6. What property is the same across all types of electromagnetic radiation in a vacuum? All types of electromagnetic radiation travel at the same speed in a vacuum, the speed of light. Applications of technology using electromagnetic radiation With your partner, choose a type of electromagnetic radiation and research a technology that uses that specific type of radiation. Then, answer the questions below using NASA’s “Tour of the Electromagnetic Spectrum” and outside resources if necessary. The Science News archive is one of many useful resources. Use your answers to give a brief presentation on the technology to your classmates. 1. Does the video mention a technology you already knew about that uses electromagnetic radiation? Is there an application of that technology