Frequency and Wavelength

Grade Level / Subject:

7 - High School / Science

Technology:

Limited to Moderate

Curriculum Standard:

PS- M-C3, PS-H-G1, SI-M-A1, SI-M-A3, SI-MA5, SI-M-A7

Overview:

Students should have an understanding of the Scientific Method. Using a flexible spring the students, in groups of four, will create waves explaining the relationship of wavelength and frequency.

Purpose:

This lesson is designed for students to apply the Scientific Method while gaining an understanding of wavelength and frequency.

Objectives:

Students will be able to:

Sketch and label a transverse wave.
Explain the relationship between a wave’s frequency and its wavelength when changing variables.

Materials:

Frequency and Wavelength Worksheet (following sheet)
Long flexible coil spring or Slinky, Meter stick, Stopwatch, Clay or some other item to mark the wave’s crest

Resources:

http://atic.phys.lsu.edu
http://maxwell.byu.edu/~masong/HTMstuff/C13A4.html
At the above site – definitions and animation of waves.
http://maxwell.byu.edu/~masong/HTMstuff/SCTOC.html
At the above site – various Physical Science concepts covered

Teacher sheet and teacher Directions:

Define terms
Crest - the high point of a wave
Trough - the low point in a wave
Wavelength - is measured from crest to crest or trough to trough
Frequency - the number of complete waves that past a given point in 1 second. (To find, number of waves/the time = frequency)
Amplitude - the height of the wave from baseline to crest.
Baseline - the resting point of the wave (middle between crest and trough.
Divide class into groups of 4.
Handout Frequency and Wavelength worksheet.
Students are to read through the activity before beginning the activity.
Students are to begin the worksheet.
1. Label the transverse wave on the worksheet using defined terms.
2. State Problem: Is there a relationship between a waves frequency and its wavelength?
3. State the Hypothesis: There is a relationship between a waves frequency and its wavelength. The data will show that higher frequency corresponds to shorter wavelengths.
4. 1-12 on work sheet.
  Students are to carry out the experiment by following the worksheet. In box A students should have two crest or two troughs creating at least one complete wave. In box 6 students should have two crest or two troughs creating at least one complete wave. In box 9 students should have at least 3 complete crest or trough sketching two complete waves. In box 11 students should sketch at least 4 crests or troughs to complete 3 waves. Frequency and wavelength may differ from group to group. Important points** for student understanding are listed on the worksheet.
  
  *Sound waves travel through the air very much as the spring wave travels down the spring, but sound waves travel faster - about 1/3 Km/sec.
  
  **The number of vibrations per second is called the “frequency” of the wave. To find the Unit of frequency use “cycles/sec”, (cycles are the number of hand vibrations (hand movements) in __ seconds divided by the number of seconds).
  
  ***Students should be creating a single wave crest-to-crest or trough-to-trough for 10 seconds. For wavelength use the meter stick.
5. 1. Controls
    Same spring, distance between group members, each trial 10 seconds time.
  2. Independent variable - single, double, triple wave
  3. Dependent variable - frequency and wavelength
6. Conclusion and Communication
  Students’ conclusion should be explained thoroughly. They should answer the question while applying the data they have gathered to back up their answer. The students should also address the hypothesis. Was it correct or incorrect, they should prove this.