Name: ______________________________________
Standing Transverse Waves on Large Coil Springs
Purpose:
•
To produce standing transverse waves in a large coil spring
and investigate relationships among frequency, wavelength,
number of loops, velocity, and tension in the spring
Equipment:
•
stopwatches, meter stick, large coil spring
Procedure:
•
Stretch the large coil spring approximately 20-30 feet. The specific length you choose
is dependent upon which particular spring you are using. Be sure to maintain this
exact distance and keep a constant tension in the spring throughout this activity.
http://www.lightandmatter.com/html_books/lm/ch20/ch20.html
•
Send a single pulse down the spring and use two timers to record the time
needed for the pulse to travel the entire length of the spring and back (40-60 feet). Use the average time and the total distance
the pulse traveled to calculate the speed of the wave. Show your measurements and calculations in the space below.
•
With the far end of the spring held firmly to the floor, move the other end of the spring back and forth until “loops” are formed.
•
Use the relationship that each loop is one-half wavelength long to determine the wavelength of the standing wave you produced.
•
Once you have formed a nice standing wave pattern, have two lab group members use stopwatches to measure the total time
needed for your arm to make ten complete back and forth motions.
•
Average the two times and record in the data table.
•
Calculate the frequency of the wave by dividing the number of cycles (10) by the average total time (f = cycles per second).
•
Calculate the speed of your wave by multiplying the frequency by the wavelength (v = fλ).
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Name: ______________________________________
•
Repeat this procedure for other standing wave patterns. Depending on the specific spring you are using, you may find it difficult to
produce a standing wave with five loops, but easy to produce one with a single loop, or difficult to produce a single loop, but easy
to produce five loops. You should have no trouble producing standing waves with two, three, and four loops.
DATA TABLE
Stretched
Spring Length,
feet
#
Loops
Wavelength,
feet
# Cycles
1
10
2
10
3
10
4
10
5
10
Total Time, sec
Stopwatch 1
Stopwatch 2
Average
Frequency,
Hz
Wave Speed,
ft/sec
Questions:
1.
How does the speed you calculated by sending a single pulse down the stretched spring compare with the speeds calculated in the
data table?
2.
How does the frequency needed to generate two loops compare with to the frequency need for one loop?
3.
How does the frequency needed to generate four loops compare with the frequency needed for two loops?
4.
Explain your responses to Questions 2 and 3.
5.
What happens to the speed of the wave as you produce different numbers of loops while maintaining a constant tension?
6.
Explain your answer to number to Question 5.
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