FREE K-12 standards-aligned STEM

curriculum for educators everywhere!

Find more at TeachEngineering.org.

Soon we will see how this simple act is representative of the nature of a physical wave. We also encountered waves in Math class in the form of the sine and cosine function. We often plotted y = B.sine(A.x) on our calculator or by hand and observed that its graphical shape resembled the characteristic shape of a wave. General Chemistry 1 is a highly interactive and engaging course that covers all topics typical of first semester General Chemistry. The course includes a multitude of formative practice problems that are scaffolded and include detailed feedback, interactives such as PhET simulations and virtual lab experiments, engaging media elements, and summative assessments.

Quick Look

Grade Level: 4 (3-5)

Time Required: 30 minutes

Expendable Cost/Group: US $1.00

(Assumes teachers have access to Slinkys® and Dominoes®)

Group Size: 2

Activity Dependency: None

Subject Areas: Physical Science

Engineering Connection

Waves are used for many reasons in our society: sonar, reading glasses, light bulbs, stereo equipment and lasers all rely on either sound or light waves. For engineers to develop new (and already used) technology, they must understand how light and sound waves work and how to use them in new devices.

Learning Objectives

After this activity, students should be able to:

• Explain what a longitudinal wave is and give an example.
• Explain what a transverse wave is and give an example.
• Create plots of sin and cosine wave functions (if using extension activity)

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.

NGSS: Next Generation Science Standards - Science

International Technology and Engineering Educators Association - Technology

• Various relationships exist between technology and other fields of study. (Grades 3 - 5) More Details

  Do you agree with this alignment? Thanks for your feedback!

State Standards

Colorado - Science

• Identify and describe the variety of energy sources (Grade 4) More Details

  Do you agree with this alignment? Thanks for your feedback!

Materials List

For each group:

• 2 copies of the Wave Worksheet
• 1 Slinky® (groups may share if there are not enough Slinkys®
• 2 meter long length of rope (about the thickness of a clothesline)
• 10 Dominoes®

More Curriculum Like This

This lesson introduces the concepts of longitudinal and transverse waves. Students see several demonstrations of waves and characterize them by transverse and longitudinal behavior.

Students learn about echolocation: what it is and how engineers use it to 'see' things in the dark, or deep underwater. They also learn how animals use echolocation to catch their meals and travel the ocean waters and skies without running into things.

Introduction/Motivation

Do you all remember what we learned about the two different types of waves? Can anyone tell me what the two types are? Super! Now can someone explain what a longitudinal wave is? Great — and how about the other wave, transverse? Who can explain how that one moves? Fabulous! And can someone give me an example of a transverse wave? How about a longitudinal wave? Terrific! Now that we have learned about the two types of waves, we are going to make some ourselves using Slinkys®. I have one more question for you — who can tell me why an engineer would need to know about waves? Well, we are going to talk more about this later on, but sound and light travel in waves, so engineers can use what they know about sound waves and light waves to build radios, televisions, light bulbs and even reading glasses. Engineers use what they have learned about waves to help people in many different ways.

Procedure

The key points to convey to the students are that a wave is a moving disturbance through a medium and that longitudinal and transverse waves move in different ways. Longitudinal waves oscillate in the same direction that they travel, while longitudinal waves oscillate in a direction perpendicular to their motion.

Before the Activity

• Gather all necessary materials.
• Make copies of the Wave Worksheet (one per student).

With the Students

Class Demonstration

1. Have the students form a circle with their right shoulders pointing towards the center.
2. Ask students to design a way for this ring of students to create a transverse wave. An idea should come up where a student raises her arms and then lowers them, and then the student behind her raises her arms and lowers them, and so on around the circle. It should be like the 'wave' in a football stadium.
3. After the students have the hang of it, ask them what the disturbance in the wave was. (Answer: Their raised, then lowered, arms were the disturbance.)
4. Ask them if the disturbance travels up and down or horizontally around the circle. (Answer: up and down)
5. Ask them if the wave traveled horizontally around the circle or up and down. (Answer: around the circle) The disturbance oscillating perpendicular to the direction the wave travels is the definition of a transverse wave.
6. Still standing as in Demo #1, ask the students to describe which direction the disturbance would travel in the ring if the students wanted to make a longitudinal wave. The students should say that the disturbance needs to travel in the same direction as the wave, and around the ring.
7. Ask students how can they make a longitudinal wave? Have one student gently push the back of the student in front of her, and then the pushed student should gently push the student in front of her and so on, this will make a longitudinal wave traveling around the ring.
8. Ask students: What is the disturbance? (Answer: the push) Is the disturbance traveling up and down or around the ring? (Answer: around the ring) Which way does the wave travel? (Answer: around the ring) Because this disturbance travels in the same direction as the wave, it is a longitudinal wave.

Student/Team Demonstration

1. Break students into groups of 2.
2. Give each group a Slinky®, rope and 10 Dominoes®.
3. Ask them to work with their partner to create longitudinal and transverse waves using all of these items. Most likely they will be able to create both longitudinal and transverse waves with the Slinkys®, but only transverse waves with the rope and longitudinal waves with the dominoes. (Note: Be sure to give the students plenty of time and room to experiment on their own.)
4. Instruct students to complete the Wave Worksheet.

Vocabulary/Definitions

longitudinal wave: A wave whose particles oscillate in the same direction as the wave travels.

oscillate: To vibrate back and forth.

transverse wave: A wave whose particles oscillate perpendicular to the direction that the wave travels.

wave: A traveling disturbance in a medium.

Assessment

Pre-Activity Assessment

Class Review: Briefly review the different types of waves with the students before starting the activity.

Activity Embedded Assessment

Group Discussion: While the class is gathered in a circle, be sure to ask for student input before creating the different types of waves together. If you like, give students time to turn to the person next to them and come up with an idea for creating the wave. This encourages independent creative thinking, without letting the teacher give all the answers right away.

Post-Activity Assessment

Wave Worksheet: With 10 minutes left in class, ask students to complete the Wave Worksheet.

Unit 4: The Wave Nature Of Lightmr.'s Learning Website Site

Patterns: Using their observationsa asks students to discuss patterns that can be used to predict future motion.

Share With the Class!: Invite students to share with the class how they used the materials to create the different types of waves. Encourage them (as time allows) to demonstrate their methods to the rest of the class. Make sure they explain which type of wave they are demonstrating.

Safety Issues

During the Class Demonstration, ensure that students do not push each other hard, as a student could hit their head on the other student's back.

Remind students not to roughhouse or hurt each other when using the ropes and Slinkys®.

Activity Extensions

Students can conduct the 'Slinky in Hand: Making Waves' activity from the Exploratorium Snacks website at: http://www.exploratorium.edu/snacks/slinkyinhand/index.html.

Student may visit http://www.acs.psu.edu/drussell/Demos.html for excellent animations of longitudinal and transverse wave behavior.

Activity Scaling

For upper grades, have students use Excel® to create plots of sin and cosine wave functions. For lower grades, do activity as is.

References

Exploratorium, The museum of science, art and human perception at the Palace of Fine Arts, Exploratorium Snacks: Science, 'Slinky in Hand,' accessed January 25, 2007. http://www.exploratorium.edu/snacks/slinkyinhand/index.html

Unit 4: The Wave Nature Of Lightmr.'s Learning Website Learning

Russel, Dan, 1999. KetterlingUniversity Applied Physics, Acoustics Animations, 'Longitudinal and Transverse Wave Motion,' accessed January 18, 2007. http://www.acs.psu.edu/drussell/Demos/waves/wavemotion.html

University of Chicago, Center for Astrophysical Research in Antarctica, 'Waves: An Introduction,' September 11, 1999, accessed January 25, 2007. http://astro.uchicago.edu/cara/outreach/se/ysi/1999/intro2.html

Acknowledgements

The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education, and National Science Foundation GK-12 grant no 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.

Last modified: January 19, 2021

• Plane waves
  • Amplitude and intensity
  • The speed of sound
• Circular and spherical waves
  • Attenuation
  • Impedance
  • Interference
  • Moving sources and observers
• Standing waves
  • In stretched strings
  • In air columns
  • In nonharmonic systems
• Steady-state waves
  • Spectral analysis
  • Generation by musical instruments
• Hearing

Our editors will review what you’ve submitted and determine whether to revise the article.

Sound, a mechanical disturbance from a state of equilibrium that propagates through an elastic material medium. A purely subjective definition of sound is also possible, as that which is perceived by the ear, but such a definition is not particularly illuminating and is unduly restrictive, for it is useful to speak of sounds that cannot be heard by the human ear, such as those that are produced by dog whistles or by sonar equipment.

The study of sound should begin with the properties of sound waves. There are two basic types of wave, transverse and longitudinal, differentiated by the way in which the wave is propagated. In a transverse wave, such as the wave generated in a stretched rope when one end is wiggled back and forth, the motion that constitutes the wave is perpendicular, or transverse, to the direction (along the rope) in which the wave is moving. An important family of transverse waves is generated by electromagnetic sources such as light or radio, in which the electric and magnetic fields constituting the wave oscillate perpendicular to the direction of propagation.

Sound propagates through air or other mediums as a longitudinal wave, in which the mechanical vibration constituting the wave occurs along the direction of propagation of the wave. A longitudinal wave can be created in a coiled spring by squeezing several of the turns together to form a compression and then releasing them, allowing the compression to travel the length of the spring. Air can be viewed as being composed of layers analogous to such coils, with a sound wave propagating as layers of air “push” and “pull” at one another much like the compression moving down the spring.

A sound wave thus consists of alternating compressions and rarefactions, or regions of high pressure and low pressure, moving at a certain speed. Put another way, it consists of a periodic (that is, oscillating or vibrating) variation of pressure occurring around the equilibrium pressure prevailing at a particular time and place. Equilibrium pressure and the sinusoidal variations caused by passage of a pure sound wave (that is, a wave of a single frequency) are represented in Figure 1A and 1B, respectively.

Plane waves

A discussion of sound waves and their propagation can begin with an examination of a plane wave of a single frequency passing through the air. A plane wave is a wave that propagates through space as a plane, rather than as a sphere of increasing radius. As such, it is not perfectly representative of sound (see below Circular and spherical waves). A wave of single frequency would be heard as a pure sound such as that generated by a tuning fork that has been lightly struck. Fun home cast recording download. As a theoretical model, it helps to elucidate many of the properties of a sound wave.

Wavelength, period, and frequency

Free vdi solution. Figure 1C is another representation of the sound wave illustrated in Figure 1B. As represented by the sinusoidal curve, the pressure variation in a sound wave repeats itself in space over a specific distance. This distance is known as the wavelength of the sound, usually measured in metres and represented by λ. As the wave propagates through the air, one full wavelength takes a certain time period to pass a specific point in space; this period, represented by T, is usually measured in fractions of a second. In addition, during each one-second time interval, a certain number of wavelengths pass a point in space. Known as the frequency of the sound wave, the number of wavelengths passing per second is traditionally measured in hertz or kilohertz and is represented by f.

There is an inverse relation between a wave’s frequency and its period, such that

This means that sound waves with high frequencies have short periods, while those with low frequencies have long periods. For example, a sound wave with a frequency of 20 hertz would have a period of 0.05 second (i.e., 20 wavelengths/second × 0.05 second/wavelength = 1), while a sound wave of 20 kilohertz would have a period of 0.00005 second (20,000 wavelengths/second × 0.00005 second/wavelength = 1). Between 20 hertz and 20 kilohertz lies the frequency range of hearing for humans. The physical property of frequency is perceived physiologically as pitch, so that the higher the frequency, the higher the perceived pitch. There is also a relation between the wavelength of a sound wave, its frequency or period, and the speed of the wave (S), such that

Amplitude and intensity

Mathematical values

The equilibrium value of pressure, represented by the evenly spaced lines in Figure 1A and by the axis of the graph in Figure 1C, is equal to the atmospheric pressure that would prevail in the absence of the sound wave. With passage of the compressions and rarefactions that constitute the sound wave, there would occur a fluctuation above and below atmospheric pressure. The magnitude of this fluctuation from equilibrium is known as the amplitude of the sound wave; measured in pascals, or newtons per square metre, it is represented by the letter A. The displacement or disturbance of a plane sound wave can be described mathematically by the general equation for wave motion, which is written in simplified form as:

This equation describes a sinusoidal wave that repeats itself after a distance λ moving to the right (+ x) with a velocity given by equation (2).

Unit 4: The Wave Nature Of Lightmr.'s Learning Website Free

The amplitude of a sound wave determines its intensity, which in turn is perceived by the ear as loudness. Acoustic intensity is defined as the average rate of energy transmission per unit area perpendicular to the direction of propagation of the wave. Its relation with amplitude can be written aswhere ρ is the equilibrium density of the air (measured in kilograms per cubic metre) and S is the speed of sound (in metres per second). Intensity (I) is measured in watts per square metre, the watt being the standard unit of power in electrical or mechanical usage.

The value of atmospheric pressure under “standard atmospheric conditions” is generally given as about 10⁵ pascals, or 10⁵ newtons per square metre. The minimum amplitude of pressure variation that can be sensed by the human ear is about 10^-5pascal, and the pressure amplitude at the threshold of pain is about 10 pascals, so the pressure variation in sound waves is very small compared with the pressure of the atmosphere. Under these conditions a sound wave propagates in a linear manner—that is, it continues to propagate through the air with very little loss, dispersion, or change of shape. However, when the amplitude of the wave reaches about 100 pascals (approximately one one-thousandth the pressure of the atmosphere), significant nonlinearities develop in the propagation of the wave.

Nonlinearity arises from the peculiar effects on air pressure caused by a sinusoidal displacement of air molecules. When the vibratory motion constituting a wave is small, the increase and decrease in pressure are also small and are very nearly equal. But when the motion of the wave is large, each compression generates an excess pressure of greater amplitude than the decrease in pressure caused by each rarefaction. This can be predicted by the ideal gas law, which states that increasing the volume of a gas by one-half decreases its pressure by only one-third, while decreasing its volume by one-half increases the pressure by a factor of two. The result is a net excess in pressure—a phenomenon that is significant only for waves with amplitudes above about 100 pascals.