The phonon is a quantum of an elastic wave in a crystal lattice.

The correct answer is: True.

A phonon is a quantum of an elastic wave in a crystal lattice. It is a quasiparticle that represents the quantum of energy of a sound wave in a solid. Phonons are bosons, which means that they obey Bose-Einstein statistics. This means that they can occupy the same quantum state, and that they can condense into a Bose-Einstein condensate at low temperatures.

Phonons play an important role in the thermal conductivity of solids. They also play a role in the electrical conductivity of semiconductors.

The following is a brief explanation of each option:

• Option A: True. Phonons are quanta of an elastic wave in a crystal lattice.
• Option B: False. Phonons are not waves. They are quasiparticles that represent the quantum of energy of a sound wave in a solid.

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