⏱ Phase 1: Intro (0–15 min)
πŸ”¬ Phase 2: Investigation (15–40 min)
βœ“ Phase 3: Review (40–50 min)
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50:00
Grade 8 Β· Physics Β· Wave Investigations Β· Part 2

WaveLab 2

Use the PhET simulation below to investigate the properties of waves. Follow each investigation step-by-step, record your measurements, and discover the relationships yourself.

Wavelength Period & Frequency Wave Speed v=fΞ» Transverse vs Longitudinal Frequency ↔ Wavelength Amplitude ↔ Speed

πŸŽ₯ 50-Minute Teams Session Guide β€” Ahmad Ghozlan

1
0–15 min Β· You share screen: Open this page on your screen. Share screen on Teams. Walk through the PhET sim controls together β€” show students how to use the oscillator, ruler, and timer. Demonstrate Investigation 1 (transverse vs longitudinal) live. Tell students: "Now open this link on your device and work through Investigations 2–5 independently."
2
15–40 min Β· Students work independently: Students have the link open on their own devices. You monitor Teams chat for questions. Stay on the call β€” answer questions verbally. The app guides them step by step so they rarely need to ask. Watch your own copy to anticipate where they'll get stuck (usually Investigation 3: timing the period).
3
40–50 min Β· You share screen again: Go through the answers together. Ask students to share their v=fΞ» values β€” they should all get ~the same answer. Discuss the amplitude-speed discovery. Students submit before the session ends. Check Google Sheets live to see who submitted.
🌊 PhET Simulation β€” Wave on a String
University of Colorado Boulder Β· Free Β· No install needed
Live Simulation
The simulation loads from PhET's servers (University of Colorado). Click to launch. If it doesn't load, open it in a new tab and keep this worksheet alongside.
πŸ“‹ How to Use the Simulation β€” Read Before Starting
β–Ό
1
At the top of the sim, select "Oscillate" mode (not Manual or Pulse). This creates a continuous wave.
2
Set Damping to zero (slider all the way left) so the wave doesn't fade.
3
Use the Frequency slider to control how fast the source oscillates (in Hz).
4
Use the Amplitude slider to control the height of the wave.
5
Click "Rulers" checkbox to show the ruler β€” drag it to measure distances on the wave.
6
Click "Timer" checkbox to show the stopwatch β€” use it to measure the period T.
7
Press Pause ⏸ to freeze the wave for measurements β€” much easier than measuring a moving wave!
Oscillate Mode
Creates a continuous travelling wave β€” use this for all investigations
Rulers
Drag the ruler to measure wavelength (crest to crest distance)
Timer
Start timer, watch one full oscillation, stop β€” that's your period T
Pause Button
Freeze the wave to take measurements accurately
πŸ”¬ Wave Investigations
0 / 5 completed
1
Transverse vs Longitudinal Waves
Observe and distinguish the two types of wave
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β–Ό
Step 1 β€” Set up
In the PhET sim: βš™ Select "Oscillate" then look at the bottom-left panel. You should see options for wave type. Set it to Transverse first. Observe the motion of the string particles β€” which direction do they move compared to the wave's travel direction?
Step 2 β€” Observe & Record
Now switch to Longitudinal (sound wave mode). Observe how the coils compress and expand. Compare both types.
Conclusion
2
Measuring Wavelength (Ξ»)
Use the ruler to measure crest-to-crest distance
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β–Ό
Setup
Switch back to Transverse mode. Set frequency to 1.50 Hz. Set amplitude to 0.75 cm. Set damping to zero. Wait for the wave to develop fully (3–4 seconds).
Measure
⏸ Pause the simulation. Enable the πŸ“ Ruler. Drag the ruler to measure the distance from one crest to the very next crest. This distance is the wavelength Ξ».
Hz
cm β€” crest to crest
Define in your own words
3
Period (T) and Frequency (f)
Measure the period and calculate frequency using f = 1/T
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β–Ό
Setup
Keep the same settings (f = 1.50 Hz). Enable the ⏱ Timer in the sim. Unpause if paused. Watch the end of the string (the source) oscillate up and down.
Measure Period T
Watch the source. The moment it starts moving upward from the centre, start the timer. Stop when it returns to exactly that same position after one complete oscillation. This time is the period T.
seconds β€” one full oscillation
β€” Enter T above
Hz β€” calculated
Hz β€” read from slider
Relationship between T and f
4
Wave Speed: v = fΞ»
Calculate wave speed and verify with the simulation
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β–Ό
Calculate
Using your measurements from Investigations 2 and 3, calculate the wave speed using v = f Γ— Ξ». Make sure to convert Ξ» from cm to metres first (divide by 100).
metres (divide cm by 100)
β€” Enter f and Ξ» above
m/s
Verify with Simulation
Now change the frequency slider to 2.00 Hz. Pause the sim and measure the new wavelength. Calculate the new speed using v = fΞ». Is the wave speed the same or different?
β€”
What did you discover about wave speed?
5
Effect of Frequency on Wavelength
Discover the inverse relationship between f and Ξ»
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β–Ό
Data Collection
Set three different frequencies in the sim. For each one, pause and measure the wavelength. Record in the table below. Keep all other settings the same (same tension, same amplitude).
Trial Frequency f (Hz) Wavelength Ξ» (cm) Speed v=fΞ» (m/s)
1 β€”
2 β€”
3 β€”
Conclusion β€” The Relationship
β˜…
Bonus β€” Does Amplitude Affect Wave Speed?
Challenge your intuition β€” test a common misconception
Optional
β–Ό
Prediction First
Before testing β€” make a prediction. If you increase the amplitude of the wave, do you think the wave will travel faster, slower, or at the same speed? Write your prediction first, then test it.
Test It
Set frequency to 1.50 Hz. Try three different amplitudes (low, medium, high). For each, measure the wavelength and calculate v = fΞ». Does the speed change?
Enter all three Ξ» values
AI Tutor β€” Was your prediction correct?

πŸ“Š Submit Your Investigation Results

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Score

Ahmad reviews your investigation findings and wave speed calculations in the next class.