## Can You See the Music?

### Warren Bell

#### Description

The students learn the makeup of the electromagnetic spectrum and how the various forms of EMRs are similar and different from each other.

#### Objectives

Uses systems of equations and inequalities to solve real world problems graphically, algebraically, and with matrices.

The student knows that as electrical charges oscillate, they create time-varying electric and magnetic fields that propagate away from the source as an electromagnetic wave.

#### Materials

-Strobe light
-Microwave oven (optional)
-Black light and/or infrared light source (optional)
-X-ray film (optional)
-Handout of electromagnetic spectrum, one copy per student (See Preparations)
-Handout of Wavelength, Frequency, Energy comparison chart, one copy per student (See Preparations)
-Handout of Mathematical Relationships of Wavelength, Energy, and Frequency, one copy per student (See Preparations)
-Handout of Radiation Energy Formulae, one copy per student (See Associated File)
-Electromagnetic Radiation Worksheet, one copy per student (See Associated File)
-Electromagnetic Radiation Worksheet Thought Questions, one copy per student (See Associated File)

#### Preparations

1. Assemble all equipment necessary for the activity.
4. Download the Mathematical Relationships of Wavelength, Energy, and Frequency from the Csep Website at http://csep10.phys.utk.edu/astr162/lect/light/waves.html.
7. Download and copy the Electromagnetic Radiation Worksheet Thought Questions, one copy per student. (See Associated File)

#### Procedures

NOTE: This lesson utilizes algebraic solving skills, equation manipulation and formulas.

DAY 1
1. Turn on a strobe light with a radio tuned to a rock station as the students enter the classroom.

2. After the students take their seats, ask them what the strobe light and the music playing from the radio have in common.

3. Encourage students' responses by describing aspects of the electromagnetic spectrum that they see and use in their daily lives (e.g., microwave ovens, TV, sunlight, x-rays).

5. Tell the students to answer the questions at the bottom of the chart.

6. Briefly discuss the students' answers to the questions and emphasize that all the various forms of EMRs have certain things in common: created by accelerated charges; are in the form of a wave motion; travel at the speed of light through space or vacuum; are polarized; and are transverse in nature.

7. Emphasize that all EMRs differ in certain aspects with regard to their energies, frequencies and their wavelengths by going over the Wavelengths, Frequency, and Energy comparison chart downloaded from the Imagine Website. (See Weblinks)

8. Ask the students to determine the relationship between the energy content of an EMR and the frequency of the EMR. (What happens to the frequency as the energy is increased?) ANS. Direct relationship – frequency increases with increasing energy.

9. Ask the students to determine the relationship between the energy content of an EMR and the wavelength of the EMR. (What happens to the wavelength of an EMR as the energy is increased?) ANS. Inverse relationship – wavelength becomes shorter with increasing energy.

DAY 2
10. Discuss the Mathematical Relationships of Wavelength, Energy, and Frequency with regard to the information ascertained on the handouts from the Csep Website at http://csep10.phys.utk.edu/astr162/lect/light/waves.html.

11. Tell the students to review the variations of the base formula on the Radiation Energy Formulae sheet (See Associated File) or have the students derive the variations from the original formulas.

12. Tell the students to solve the example problems and the thought questions on the Electromagnetic Radiation Worksheets found in the associated files.

13. Allow the students to work individually or in pairs to enhance learning for the majority of the class period. While the students are working on the problems and questions, circulate throughout the class helping students with the problems. Spot check students' worksheets to make sure they are on track with their calculations.

14. Tell the students to submit their finished worksheets at the end of class for assessment purposes. (An answer key for the Electromagnetic Radiation Worksheet is located in the associated file. See Assessments for additional assessment criteria.)

#### Assessments

The teacher assesses each student by the following criteria:

1. The student knows what an electromagnetic wave is and the different forms by which it can be observed and measured evidenced by the ability to define electromagnetic radiation and list five forms in which it exists.

2. The student knows the five common factors of all EMRs and their three primary differences evidenced by the ability to illustrate by diagrams the five common factors that all EMRs share.

3. The student knows that there is a direct relationship between the energy and frequency of an EMR evidenced by the ability to show, by use of formulas, the three major differences in EMRs.

4. The student knows that there is an inverse relationship between the energy and wavelength of an EMR evidenced by the ability to show, by use of equations, the direct relationship between energy and frequency.

5. The student is able to determine the amount of energy needed to create an EMR in the visible light range for the major spectral colors (ROYGBIV) given their pure color Angstrom readings evidenced by the ability to solve various problems involving energy, frequency and wavelength utilizing algebraic skills.

Electromagnetic spectrum chart and numerical values
MicroWorlds

Web supplement for Can You See the Music?
chem-ed/light

Wavelength, Frequency, and Energy comparison chart from Imagine
Aastronomy Notes