In this episode of The Dead Scientists, we delve into Richard Feynman’s explanation of the fascinating phenomenon of beats. Feynman introduces how beats occur when two waves with slightly different frequencies interfere, producing a wave with an average frequency and a pulsating intensity. The beat frequency is determined by the difference between the two original frequencies.
We explore the application of this concept in amplitude modulation (AM) radio waves, where the amplitude of a carrier wave is modulated by an audio signal, leading to the creation of sidebands. Feynman also tackles the apparent paradox of wave propagation in materials with a refractive index, explaining how the phase velocity can exceed the speed of light while the group velocity, which carries information, remains below light speed.
Lastly, we examine how beats help us understand energy transfer through the example of coupled pendulums, illustrating how the superposition of two waves with different frequencies enables the exchange of energy between two systems.
Whether you’re a physics enthusiast or curious about wave phenomena, this episode provides an engaging look into the intricate world of beats, modulation, and wave propagation, brought to life through Feynman’s insightful explanations.

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