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Interactive
University of Colorado

University of Colorado: Ph Et Interactive Simulations: Fourier Making Waves

For Students 9th - 10th
Learn how to make waves of all different shapes by adding up sines or cosines. Make waves in space and time and measure their wavelengths and periods. See how changing the amplitudes of different harmonics changes the waves. Compare...
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Activity
Wolfram Research

Wolfram Math World: Fourier Transform Exponential Function

For Students 9th - 10th
This site explains how the Fourier transform of an exponential function is related to the Lorentzian function. Site also contains relevant links.