Superposition & Standing Waves Simulation — ClassAdapt
What the simulation shows
Two animated wave tubes float in 3D space at different depths, with a third white resultant tube running between them. Students can orbit the camera, zoom, and watch the waves update in real time as they adjust the controls.
Superposition tab
Wave 1 (cyan) and Wave 2 (amber) both travel rightward along parallel paths. A white Combined Wave sits between them, showing the result of adding the two displacements at every point. The Phase difference slider runs from 0° to 180°, and three things update simultaneously as students drag it: the shape of the white wave, a colour-coded interference banner across the bottom, and the teaching panel on the left.
At 0° (in phase), the white wave is tall and clean — double the amplitude of either component. As the slider moves toward 180°, the white wave shrinks progressively until at full antiphase it collapses to a flat line. The banner shifts from green (Constructive interference — amplitude doubles) through amber (Partial interference) to red (Destructive interference — waves cancel out). A wavelength annotation floats above the cyan crest and follows it across the screen as the wave travels.
Standing wave tab
The cyan wave now travels rightward and the amber wave travels leftward, shown by direction arrows on each axis. The white resultant becomes a standing wave — it oscillates but its shape never moves along the medium. Red node markers (N) sit at fixed positions where displacement is permanently zero. Green antinode markers (A) pulse up and down at the positions of maximum displacement, moving with the wave but never drifting left or right. Dashed envelope curves trace the maximum possible displacement at each position.
The λ/2 bracket annotates the gap between two adjacent nodes with a double-headed arrow. A 2A bracket on the first antinode shows the maximum amplitude. Two short explanation panels are fixed bottom-right: “N = node (zero displacement)” and “A = antinode (max displacement = 2A).”
Suggested Class Activity
“What happens when two waves meet?”
Duration: 30 minutes | Level: GCSE Physics Y10–11 | Prior knowledge: wave properties (amplitude, wavelength, frequency)
1. The question (3 min)
Open the Superposition tab with the Phase difference slider at 0°. Without explaining anything, ask:
“Two waves are travelling through the same medium at the same time. What do you think the combined wave will look like — bigger, smaller, or the same?”
Take three or four answers. Most students will guess “bigger.” Some may say “it depends.” Do not confirm or correct yet. Show the screen — the white wave is clearly taller than either component. Then ask: “What if the two waves were perfectly out of step with each other?”
Drag the slider slowly to 180°. The white wave shrinks to nothing. Let this settle.
“Both waves are still there. Neither has stopped. But in the places where one wave pushes up, the other pushes down by exactly the same amount — so the total displacement is zero.”
2. The principle (5 min)
State the rule clearly:
“The Principle of Superposition: when two waves meet, the total displacement at any point is the sum of the individual displacements at that point.”
Demonstrate with the slider at 0°: both waves push up together — the sum is 2A. Demonstrate at 180°: one pushes up exactly as much as the other pushes down — the sum is zero.
Ask students to write the principle in their own words before you move on.
3. Predict, test, explain (10 min)
Students work individually through these four positions. For each, they predict the combined wave shape, then test it in the simulation.
| Position | Prediction | What they see | Key term |
|---|---|---|---|
| φ = 0° | — | Double amplitude | Constructive interference |
| φ = 90° | — | Medium amplitude | Partial interference |
| φ = 180° | — | Flat line | Destructive interference |
| φ = 90° again | — | Same as before | Symmetric |
After the table: “What pattern do you notice? What does it tell you about interference?”
Then switch to the Standing Wave tab without explaining what it is.
“I’ve changed something about Wave 2. Look carefully. What is different?”
Students should notice the amber wave now has a leftward arrow. Some will notice the white wave no longer travels — it just oscillates up and down in place. Ask them to describe what they see before naming it.
4. Standing waves (8 min)
Name the features:
“A standing wave is formed when two waves of the same frequency and amplitude travel in opposite directions through the same medium. The result is a wave that appears to stand still.”
Point to the N markers:
“These are nodes — points where the displacement is always zero, no matter what. The two waves always cancel here.”
Point to the A markers, which are pulsing:
“These are antinodes — points where the displacement is always at its maximum. The two waves always reinforce here.”
Ask students to identify the λ/2 bracket annotation:
“The distance between two adjacent nodes is always half a wavelength. If you can measure the node spacing, you can find the wavelength.”
Ask: “Is energy being transferred along the medium by this standing wave?” (Answer: no — key GCSE exam point.)
5. Exam question (4 min)
“A standing wave is set up in a string of length 60 cm. There are four nodes along the string, including one at each end. Calculate the wavelength of the wave.”
Model answer: 4 nodes including the ends means 3 half-wavelengths fit in 60 cm. λ/2 = 20 cm, so λ = 40 cm.
Adaptation notes for ClassAdapt
- Reduce Motion in the SEND panel stops the wave animation — useful while students are reading labels or copying notes, so the motion doesn’t compete for attention
- The Phase difference slider gives non-verbal learners a direct physical action (drag) that immediately changes the outcome — cause and effect without needing to read an explanation first
- The N and A labels are colour-coded and positioned directly beside their corresponding markers — no line from label to object for students to track
- Students who find the 3D view disorienting can double-click to reset the camera to the default front-facing angle at any time