Lesson: Electromagnetic Radiation

Contributed by: VU Bioengineering RET Program, School of Engineering, Vanderbilt University

A diagram of the electromagnetic spectrum shows different types of electromagnetic radiation ordered by increasing frequency (in hertz). The most familiar form of electromagnetic radiation is visible light (center), with infrared (IR) and ultraviolet (UV) light on either side. The higher frequencies of EM radiation (right) consisting of x-rays and gamma rays, are types of ionizing radiation. Lower frequency radiation (left), consisting of light, infrared (IR), microwave (MW), radio frequency (RF), and extremely low frequency (ELF) are types of non-ionizing radiation.
Ultraviolet is a type of electromagnetic radiation that can lead to risks of skin cancer.
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Copyright © 2008 OSHA Safety and Health Topics, Wikimedia Commons http://commons.wikimedia.org/wiki/File:OSHA_radiation_spectrum.jpg

Summary

Students are presented with a hypothetical scenario that delivers the unit's Grand Challenge Question: To apply an understanding of nanoparticles to treat, detect and protect against skin cancer. Towards finding a solution, they begin the research phase by investigating the first research question: What is electromagnetic energy? Students learn about the electromagnetic spectrum, ultraviolet radiation (including UVA, UVB and UVC rays), photon energy, the relationship between wave frequency and energy (c = λν), as well as about the Earth's ozone-layer protection and that nanoparticles are being used for medical applications. The lecture material also includes information on photo energy and the dual particle/wave model of light. Students complete a problem set to calculate frequency and energy.
This engineering curriculum meets Next Generation Science Standards (NGSS).

Engineering Connection

As the first step in the engineering design process, engineers must fully understand the problem. To do this, they research all relevant science and math concepts, as well as all previous and current engineering designs related to the subject. As students tackle the challenge question, they learn background information on the science of ultraviolet light. They also learn about the impact of human-generated pollution on the ozone layer and its connection to public health through increased incidences of skin cancer—an environmental engineering connection. In addition, they learn that biomedical engineers are researching ways to use nanoparticles to diagnose and treat cancer because they are good imaging agents.

Learning Objectives

After this lesson, students should be able to:

  • Calculate frequency or wavelength for electromagnetic radiation.
  • Calculate the energy of a photon.
  • List components of the electromagnetic spectrum in order of increasing energy.
  • Explain that energy given to an electron is quantized.
  • Explain what biomedical engineers study.

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Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

  • Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other. (Grades 9 - 12) Details... View more aligned curriculum... Do you agree with this alignment?
  • Analyze a major global challenge to specify qualitative and quantitative criteria and constraints for solutions that account for societal needs and wants. (Grades 9 - 12) Details... View more aligned curriculum... Do you agree with this alignment?
  • Design a solution to a complex real-world problem by breaking it down into smaller, more manageable problems that can be solved through engineering. (Grades 9 - 12) Details... View more aligned curriculum... Do you agree with this alignment?
  • Solve linear equations and inequalities in one variable, including equations with coefficients represented by letters. (Grades 9 - 12) Details... View more aligned curriculum... Do you agree with this alignment?
  • Medical technologies include prevention and rehabilitation, vaccines and pharmaceuticals, medical and surgical procedures, genetic engineering, and the systems within which health is protected and maintained. (Grades 9 - 12) Details... View more aligned curriculum... Do you agree with this alignment?
  • The process of engineering design takes into account a number of factors. (Grades 9 - 12) Details... View more aligned curriculum... Do you agree with this alignment?
  • Calculate the wavelength, frequency and energy of a photon of electromagnetic radiation. (Grades 9 - 12) Details... View more aligned curriculum... Do you agree with this alignment?
  • Understand the mathematical principles associated with the science of chemistry. (Grades 9 - 12) Details... View more aligned curriculum... Do you agree with this alignment?
  • Utilize appropriate mathematical equations and processes to solve chemistry problems. (Grades 9 - 12) Details... View more aligned curriculum... Do you agree with this alignment?
  • Describe the dynamic interplay among science, technology, and engineering within living, earth-space, and physical systems. (Grades 9 - 12) Details... View more aligned curriculum... Do you agree with this alignment?
Suggest an alignment not listed above

Introduction/Motivation

You have just been given the following grand challenge: "Congratulations! You have just won the Nobel Prize in chemistry for your work with nanoparticles!! You have now decided to fulfill your lifelong dream of learning how to surf by using your 1.4 million dollar monetary prize to move to Einstein Cove, Australia. However, upon researching your move, you come across the ultraviolet index information for Australia. What does this mean in terms of your potential skin cancer risk as a surfing enthusiast in Einstein Cove? How could you use your expertise in nanoparticles to treat, detect and protect against skin cancer?"

A graph plots the daily UV index (0 to 15) from January through December. The resulting line, while somewhat jagged, basically forms a bell curve that peaks during the June, July and August summer months, rated as "very high" and "extreme," while the winter months rate in the "low" to "moderate" categories.
An example daily UV index for Denver, CO, for 2013.
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Copyright © National Weather Service, Climate Prediction Center, NOAA http://www.cpc.ncep.noaa.gov/products/stratosphere/uv_index/gif_files/den_13.png

Biomedical engineers are increasingly looking into nanoparticles to find ways to diagnosis and treat skin cancer because nanoparticles are particularly good imaging agents. What are nanoparticles? And how could they be used to treat, detect and protect against skin cancer? What exactly is skin cancer? And what is the cause? These are just a few of the questions we investigate during the next few days in our lesson on using nanoparticles to detect, treat and protect against skin cancer.

Lesson Background and Concepts for Teachers

Legacy Cycle Steps for this Lesson

(Generate Ideas) Ask students the following research question: What is electromagnetic radiation? In class, have students write journal entries to answer the following questions:

  1. What are your initial ideas about how this question can be answered?
  2. What do you already know about UV light and nanoparticles?

(Multiple Perspectives) As a class, have students share ideas from their journals. Record their ideas on the board.

(Research and Revise) Deliver to students the lecture information on the electromagnetic spectrum, ultraviolet radiation (including UVC, UVB, and UVA rays), photon energy, and the relationship between, frequency, wavelength and energy.

(Test Your Mettle) Assign students to complete the Energy Homework questions and problems as homework or classwork.

(Go Public) Upon returning to class or completing the problem set, have students work the problems on the classroom board and discuss the answers if all students are not in agreement.

Lecture Information

Ultraviolet light is a form of electromagnetic radiation. Electromagnetic radiation is a form of radiant energy that exhibits wavelike behavior and travels through space at the speed of light in a vacuum. The entire range of frequencies and wavelengths that make up all forms of electromagnetic radiation, including radio waves, gamma rays and ultraviolet waves is called the electromagnetic spectrum.

A diagram shows the full range of the electromagnetic spectrum from (left to right) gamma waves, x-rays, ultraviolet, visible spectrum, IR, microwave, FM radio waves, AM radio waves, long radio waves, indicating the frequency and wavelength. An enlargement of the visible spectrum shows the violet-blue-green-yellow-orange-red color spectrum with wavelength size indicated (400-700 nm).
The electromagnetic spectrum.
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Copyright © 2007 Philip Rowan, Wikimedia Commons http://commons.wikimedia.org/wiki/File:EM_spectrum.svg

The relationship between wave frequency, wavelength and energy is described by the equation c = λν, where c = wave speed. Wave speed in a vacuum is 3.00  108 m/s. Wavelength is the shortest distance between points where the wave pattern repeats itself, such as from crest to crest or trough to trough and is represented by the symbol λ (lambda). Wave frequency is the number of complete oscillations that a wave makes each second; it is measured in hertz and is represented by the symbol ν. Thus, the speed of the wave is equal to frequency  wavelength of the wave.

In 1900, Max Planck, a German physicist, postulated that energy is quantized and therefore must occur in discrete units of size, hν; thus, ΔE = hν. These units were called quanta of energy. Albert Einstein furthered this postulate through his Nobel Prize-winning analysis of the photoelectric effect. Einstein stated that electromagnetic radiation is also quantized. These discrete packets of electromagnetic radiation were called photons. Energy of a photon of electromagnetic energy is given by Ephoton = hν.

Combining the two equations, c = λν and Ephoton = hν, we see that Ephoton = hc/λ.

Through innovations of the combined work of Arthur Crompton, Planck and Einstein, it became evident that electromagnetic radiation has both wavelike and particle-like properties; this is now referred to as the dual nature of light. Further, Louis DeBroglie proposed that the same must also be true for matter. DeBroglie postulated that one could calculate the wavelength of a particle such as an electron given the mass and speed of the particle, through the equation m = h/λc.

A graph of ozone (DU/km) vs. altitude (km) shows the levels of ozone at varying altitudes and the amount in which the ozone levels are able to block the three types of ultraviolet radiation: UVA, UVB and UVC.
The penetrating power of ultraviolet radiation given sufficient ozone.
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Copyright © 2005 NASA, Wikimedia Commons http://commons.wikimedia.org/wiki/File:Ozone_altitude_UV_graph.jpg

The sun emits three forms of ultraviolet radiation:

  1. UVA, with a wavelength range of 315-390 nanometers
  2. UVB, with a wavelength range of 280-315 nanometers
  3. UVC, with a wavelength range of 100-280 nanometers

A large percentage—98%—of UV radiation is blocked by the ozone layer in regions with sufficient ozone. All UVC and most UVB rays are stopped by the ozone layer naturally. In turn, 90% of the UV radiation that reaches the Earth's surface is UVA. Both UVA and UVB can cause significant health risks (which will be investigated in the next lesson). Before designing any protective products, engineers must first understand the nature of ultraviolet light to understand how these rays cause skin and cancer.

Vocabulary/Definitions

electromagnetic radiation: Radiant energy that exhibits wavelike behavior and travels through space at the speed of light in a vacuum.

electromagnetic spectrum: The entire range of frequencies and wavelengths that make up all forms of electromagnetic radiation, including radio waves and gamma rays.

emission spectrum: A plot of the intensity of light emitted from a hot body over a range of frequencies.

energy: The capacity to do work or cause the flow of heat.

excited state: The state of an atom with excess energy.

frequency: The number of complete oscillations that a wave makes each second; measured in hertz.

ground state: The lowest possible energy state of an atom.

photoelectric effect: The emission of electrons by certain metals that is produced when they are exposed to electromagnetic radiation.

photon: A discrete, quantized bundle of radiation that travels at the speed of light, has zero mass, and has energy and momentum; a particle of electromagnetic radiation.

Planck constant: 6.626 X 10 to the power of negative 34 J  S

quantized: Occurring in discrete units of size, in the case of radiant hv.

quantum: One quantized packet of energy.

wavelength: The shortest distance between points where the wave pattern repeats itself, such as from crest to crest or trough to trough.

Associated Activities

  • Flame Test: Red, Green, Blue, Violet? - Students perform a flame test, gathering data that helps them identify the chemical makeup of a "mystery solution" based on the visible color the solution burns. This activity gives students practice in preparing specific molarity solutions and helps them make connections between colors, light wavelengths, and energy frequencies, which are dependent upon the molecules in the solutions.

Attachments

Assessment

Pre-Lesson Assessment

Review: Review with students the concepts about waves, wave properties and vocabulary, such as wavelength, frequency, amplitude, crest and trough. Ask them to name as many types of electromagnetic radiation as possible. (Example answers: Visible light, ultraviolet, infrared, microwaves, radio waves and gamma rays.) Show them a chart of the electromagnetic spectrum.

Post-Introduction Assessment

Research Challenge: Pose this research question to students: What is electromagnetic radiation? Then have students write journal entries to answer the following questions. As students share their answers with the class, write their ideas on the classroom board and use their answers to gauge their comprehension.

  1. What are your initial ideas about how this question can be answered?
  2. What do you already know about UV light and nanoparticles?

Lesson Summary Assessment

Brainstorming: Ask students to brainstorm in small groups the connection between electromagnetic radiation and the unit's Grand Challenge Question, as applies to skin cancer, including the potential risks and the use of nanoparticles to protect against skin cancer. Have them record their ideas about how what they learned in the lesson's lecture information could be useful in addressing the Grand Challenge Question.

Homework

Energy Homework: At lesson end, assign students to complete the 10-question Energy Homework, which requires them to use the equations and other information presented in the lesson to answer the questions and complete the problems. Refer to the Energy Homework Answer Key. Have students work the problems on the classroom board and discuss the answers if all students are not in agreement. Review students' individual answers to evaluate their depth of comprehension.

References

Zitzewitz, Paul W., et al. Physics: Principles and Problems. Columbus, OH: McGraw Hill, 2009.

Zumdahl, Steven S. and Zumdahl, Susan A. Chemistry. Seventh edition. Boston, MA: Houghton Miller Company, 2007.

Contributors

Michelle Bell, Amber Spolarich

Copyright

© 2013 by Regents of the University of Colorado; original © 2010 Vanderbilt University

Supporting Program

VU Bioengineering RET Program, School of Engineering, Vanderbilt University

Acknowledgements

The contents of this digital library curriculum were developed under National Science Foundation RET grant nos. 0338092 and 0742871. However, these contents do not necessarily represent the policies of the NSF, and you should not assume endorsement by the federal government.

Last modified: July 20, 2017

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