Lab: Measuring Waves
Name:_____________________
Purpose
In this lab you will measure wave speed, period, wavelength, and frequency of actual transverse waves
Pre-Lab
Write the definitions of the following wave terms
Wavelength
Period
Frequency
Wave speed
1.
On a long strip of paper put a dot every 5cm and draw a wave as shown, in the TOP HALF of the paper only.
Put a vertical line after each complete wave cycle. Make sure you have only complete waves on your drawing
5cm
2.
On the BOTTOM HALF of your paper, draw another wave that has exactly half the wavelength of the top one
5cm
3.
4.
Count how many full wave cycles there are on each half of your tape and record them in the tables below
Tape two pieces of paper to your desk so that there’s a vertical gap, as shown. Make sure that the tape with
the wave on it can move freely
5.
Start at the beginning of the first wave and pull the tape through the slit and time how long it takes for all the
waves to pass by the slit
Record your data in the tables and calculate period, wave speed, and frequency
6.
Trial 1
Time measured to pull all the waves through
Number of waves with wavelength = 10cm
Period of 10cm wave, (T = time ÷ # of 10cm waves)
Wave speed, v = wavelength ÷ period
Frequency, f = # of waves ÷ time
Wave speed, v = wavelength x frequency
Trial 2
Trial 3
Lab: Measuring Waves
Name:_____________________
Trial 1
Trial 2
Trial 3
Time measured to pull all the waves through (copy from
previous table)
Number of waves with wavelength = 5cm
Period of 10cm wave, (T = time ÷ # of 5cm waves)
Wave speed, v = wavelength ÷ period
Frequency, f = # of waves ÷ time
Wave speed, v = wavelength x frequency
Questions
1.
What happens to the frequency when the wavelength is shorter and both waves move at the same speed?
Use your data tables to answer this question.
Frequency of 10cm wave = ______________ Hz
Frequency of 5cm wave = _______________ Hz
2.
Answer:
Compare the wave speed of the 10cm wave and the 5cm wave. Are they the same?
3.
What would happen to the wavelength of the 10cm wave if you pulled the tape faster?
4.
What would happen to the frequency of the 10cm wave if you pulled the tape faster?
5.
What would happen to the speed of the 10cm wave if you pulled the tape faster?
6.
Write the formula for wave speed in terms of frequency and wavelength
7.
If the speed of a wave doesn’t change, explain what must happen to the wavelength if the frequency is
doubled. Refer to the formula you wrote down above.