Simulations
Interactive, watermarked science demonstrations — pick one to adjust its parameters and run it.
Beats (Two Close Frequencies)
FREEPlay two tones a few hertz apart and watch the combined wave swell and fade — the beat you hear is the difference between the two frequencies, and you can tune it to zero.
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Doppler Effect
LAUNCHFly a sound source past a fixed observer — adjust its speed, true pitch, the speed of sound, and how close it passes to hear (and see, in the compressed and stretched wavefronts) the classic pitch glide, and watch a Mach cone form once it goes supersonic.
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Sound Waves: Pitch, Loudness and Speed
FREEWatch a sound wave pass through the air. A loudspeaker pushes on the air and a row of particles wobbles back and forth about fixed spots, so patches where they are squeezed together (compressions) and spread apart (rarefactions) travel along while each particle stays where it is. Raise the frequency for a higher pitch and a shorter wavelength, raise the amplitude for a louder sound, and change the medium: sound goes 343 m/s in air, 1007 m/s in helium, 1480 m/s in water and 5960 m/s in steel. A graph shows the pressure along the wave and a microphone trace shows it over time, with the wavelength, period, speed and approximate sound level worked out for you. For instance, a 440 Hz note in air has a wavelength of 0.78 m.
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Standing Waves on a String
LAUNCHPluck a string fixed at both ends into a chosen harmonic — adjust its length, tension, and mass per unit length to see how fast, and in how many nodes and antinodes, it vibrates.
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Two-Source Wave Interference
FREETwo in-phase point sources emit circular waves — adjust the wavelength and their separation to see the exact bright/dark interference fringes form where the path lengths line up or cancel.
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