PhysicsEngineering
Wave Propagation Through Materials
Send a sound or electromagnetic wave into a slab of water, glass, concrete, metal or lead and see how much is reflected, absorbed and transmitted.
Physics
Doppler Effect
Move a sound source and an observer, change the speed of sound and the wind, and watch the observed frequency shift — all the way to a supersonic Mach cone.
- Levels
- Middle school, High school, University
- Languages
- English, Persian
- Type
- 2D · Any modern browser
- Price
- Free
- Created by
- Seyed Hamzeh Hosseini
Overview
Why does an ambulance siren sound higher as it comes toward you and lower after it passes? This simulation lets you see the answer. The source sends out circular wavefronts; when it moves, the fronts bunch up ahead of it and spread out behind it, so the observer meets crests more (or less) often.
What you can do
- Drag the source and the observer anywhere on the stage and set their speeds.
- Change the speed of sound, the source frequency and the wind.
- Jump to ready-made scenarios: approach, moving away, supersonic, wind, dense medium and slow motion.
- Watch the observed frequency on a live graph, and the Doppler formula update with your numbers.
- Turn on realistic audio and hear the pitch change once the first wavefront reaches the observer.
- Go past the speed of sound to see a Mach cone form, with the Mach angle μ = arcsin(1/M) measured on screen.
A presentation mode hides the side panel so the stage fills the projector, and the whole simulation switches between English and Persian with one click.
Learning goals
- Explain why wavefronts bunch up in front of a moving source and spread out behind it
- Predict whether the observed frequency rises or falls for different motions
- Use f′ = f (c + vₒ) / (c − vₛ) to calculate an observed frequency
- Describe how wind and the speed of sound in a medium change the result
- Relate the Mach number to the angle of a Mach cone
Teaching tips
Start with the slow motion scenario and ask students to count crests reaching the observer each second. Then switch to approach and away and have them predict the graph before you press Start. The supersonic scenario is a good bridge to sonic booms.
Related simulations
PhysicsChemistry
3D Brillouin Zone & Bragg Diffraction
Build reciprocal lattices, explore 3D Brillouin zones and simulate X-ray diffraction with Bragg’s law, structure factors, band structures and peak fitting.