Heat Transfer-1 (color)

• In most solids, the principal mode of thermal energy
assimilation is by increase in vibrational energy of the
atoms. Atoms in solids are constantly vibrating at very
high frequencies and with relatively small amplitudes. The
atomicvibrations of adjacent atoms are coupled through the
atomic bonding. These vibrations are coordinated in such
a way that traveling lattice waves are produced. (These
may be thought of as elastic waves or simply sound waves
(short wavelength and high frequency), which propagate
through a crystal at the velocity of sound. The vibrational
thermal energy for an ordered material consist of a series
of elastic waves (with a distribution of frequencies). Only
certain energies are allowed (quantization of the
vibrational energy). A single quantum of vibrational
energy is called a phonon. Note that phonon waves can
scatter free electrons during electronic conduction, thus
they control the temperature dependence of electronic
conduction