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Then try to understand what does it say about the problem.
Figure1: Normal modes of vibration progression through a crystal. The amplitude of the motion has been exaggerated for ease of viewing; in an actual crystal, it is typically much smaller than the lattice spacing.
In the similar way that photons are particles of light, phonons are particles of sound or heat. Basically, they are quantized energy, which shows wave-like and particle-like properties simultaneously.
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