Medicine Chapter 3: Ultrasound

Chapter Challenge
As ultrasound sonograms are becoming common, answers are needed to the frequent questions about how the image is made. A doctor has hired the physics students to meet the challenge of providing information to patients in the form of a written brochure, video, educational game, or series of posters.

Chapter Summary
To gain understanding of the physics principles necessary to meet this challenge, students work collaboratively on activities in which they explore sound waves, speed, frequency, measurement, and medical applications of these concepts. These experiences engage students in the content identified in the National Science Education Standards.

Activity Summaries

Physics Principles

Activity One: Measuring the Speed of Sound: Low Tech Method

Investigating the time between a sound and hearing its echo is used to introduce a simple way to measure the speed of sound. This sets the stage for more sophisticated activities with echoes and sound waves.

• Speed of sound
• Sound waves

Activity Two: Measuring the Speed of Sound: High Tech Method

Students use probes to measure the speed of sound with a computer. They also apply distance-velocity-time calculations to better understand how measurement of echoes is related to ultrasound.

• Speed of sound
• Sound waves

Activity Three: The Electronic Tape Measure

In this activity, students measure distances with an electronic tape measure, then read to learn how this tool sends out short bursts of ultrasound and detects the return of the echo.

• Ultrasound waves
• Transmission and reflection of sound waves

Activity Four: Multiple Echoes

Students continue exploring with the electronic tape measure as they attempt to measure the distance of an object that is partially shielded by another. This experience is connected back to the challenge with a reading on ultrasonic pulses.

• Energy flows
• Sound waves
• Ultrasound images
• Medical uses of ultrasound

Activity Five: Fish Finders and M Scans

Another application of echoes and sound waves is explored as students learn about sonar and fish finders. They plot graphs and calculate time, distance, and frequencies of ultrasonic waves.

• Sonar
• Sound waves
• Ultrasound images
• Medical uses of ultrasound

Activity Six: Medical "Maps"

The use of ultrasound in medicine to image organs is again the focus of this activity. After measuring and mapping their classroom with the electronic tape measure, they read about how Ultrasound B Scans are used to map the human body.

• Sound waves
• Ultrasound images
• Medical uses of ultrasound

Activity Seven: Doppler Ultrasound

In this activity, students first simulate the Doppler Effect with sounds they create. They then read about Johann Doppler and how the Doppler Effect is used in medicine to provide clearer pictures of moving objects, particularly blood.

• Sound waves - speed and crests
• Doppler Effect