Making Waves
Use a rope or string to see waves and feel their power!
Topics: Wavelength,
Waves, Energy
Materials List
 Flexible rope or
string, 5 to 7 meters
(16 to 23 feet) long
(a skipping rope
works well)
 Optional: Timer or
watch with a second
hand.
This activity can be used
to teach:
 Energy transfer (Next
Generation Science
Standards: Grade 4,
Physical Science, 3-2)
 Waves (Next
Generation Science
Standards: Grade 4,
Physical Science, 4-1,
Middle School,
Physical Science, 4-1,
4-2, High School,
Physical Science, 4-1)
Students will gain a physical sense of the relationship between energy and
wavelength as they generate waves by shaking a rope or string.
To Do and Notice
1. Two students hold the rope or string between them, a sender and a receiver.
(Students should exchange roles as they perform the exercises.)
2. One student, the sender, shakes the rope up and down rhythmically while the
other student, the receiver, holds the rope still at chest level. It will take some
exploration on the part of students to find the right speed and hand motion needed
to get specific wave patterns such as one complete wave cycle (1 crest and 1
trough) or two wave cycles.
3. Notice that shaking the rope faster will generate more wave cycles between the
ends of the rope and require more energy. Shorter wavelengths carry more
energy than longer wavelengths of the same amplitude (the height of the crest
above the centerline).
4. Place the rope on a hard surface; such as a table or smooth surfaced floor and
shake rope side to side to generate side-to-side waves. How do these waves
compare to the up and down waves?
5. Optional: Count the number of times the sender’s hand moves in 10 seconds
while generating a single wave cycle. Divide that number by 10 to calculate the
wave’s frequency. Find the frequency for a wave with 2 wave cycles.
The Science Behind the Activity
Mechanical waves carry energy and can travel in solids, liquids, and gases. Most
people are familiar with ocean waves at the beach and sound waves that travel in the
air. Light waves (electromagnetic radiation) can travel through the vacuum of space,
air, some liquids, and some solids, depending on material (medium) and wave
frequency.
The wavelength is measured as the distance from wave crest to wave crest. The
frequency of the wave is number of crests to pass a given point in a certain amount of
time (usually measured in hertz (Hz) = cycles/second). The speed of the wave is the
wavelength multiplied by the frequency.
Taking it Further


Explore sound waves with RAFT Idea Sheets Tongue Depressor Harmonica and
Buzz Off.
For more on light waves and the EM Spectrum, see RAFT Idea Sheets Holding a
Rainbow in Your Hand, The Colors of Light, and Sunlight Beads.
Web Resources (Visit www.raft.net/raft-idea?isid=210 for more resources!)

Written by Tom Gates (RAFT)
Characteristics of sound and light waves http://faculty.cord.edu/manning/physics215/studentpages/angieevanson.html
Copyright 2015, RAFT