did not become available until 1961.
It is named after Albert *Einstein.
A
- Information from the WebElements site
Einstein–Smoluchowski equa-
tionA relation between the diffu-
sion coefÜcient D and the distance
λthat a particle can jump when dif-
fusing in a time τ. The Einstein–
Smoluchowski equation, which is
D = λ^2 /2τ, gives a connection between
the microscopic details of particle dif-
fusion and the macroscopic quanti-
ties associated with the diffusion,
such as the viscosity. The equation is
derived by assuming that the parti-
cles undergo a random walk. The
quantities in the equation can be re-
lated to quantities in the *kinetic
theory of gases, with λ/τtaken to be
the mean speed of the particles and
λtheir mean free path. The Einstein–
Smoluchowski equation was derived
by Albert Einstein and the Polish
physicist Marian Ritter von Smolan-
Smoluchowski.
Einstein theory of speciÜc heat
A theory of the speciÜc heat capacity
of solids put forward by Albert Ein-
stein in 1906, in which it was as-
sumed that the speciÜc heat capacity
is a consequence of the vibrations of
the atoms of the lattice of the solid.
Einstein assumed that each atom has
the same frequency ν. The theory
leads to the correct conclusion that
the speciÜc heat of solids tends to
zero as the temperature goes to ab-
solute zero, but does not give a cor-
rect quantitative description of the
low-temperature behaviour of the
speciÜc heat capacity. In the Debye
theory of speciÜc heat, and in other
analyses of this problem, Einstein’s
simplifying approximation was im-
proved on by taking account of the
fact that the frequencies of lattice vi-
brations can have a range of values.
E-isomerSee e–z convention.
elastic collisionA collision in
which the total kinetic energy of the
colliding bodies after collision is
equal to their total kinetic energy be-
fore collision. Elastic collisions occur
only if there is no conversion of ki-
netic energy into other forms, as in
the collision of atoms. In the case of
macroscopic bodies this will not be
the case as some of the energy will
become heat. In a collision between
polyatomic molecules, some kinetic
energy may be converted into vibra-
tional and rotational energy of the
molecules.elastinAÜbrous protein that is the
major constituent of the yellow elas-
ticÜbres of connective tissue. It is
rich in glycine, alanine, proline, and
other nonpolar amino acids that are
cross-linked, making the protein rela-
tively insoluble. ElasticÜbres can
stretch to several times their length
and then return to their original size.
Elastin is particularly abundant in
elastic cartilage, blood-vessel walls,
ligaments, and the heart.
elastomerA natural or synthetic
rubber or rubberoid material, which
has the ability to undergo deforma-
tion under the inÛuence of a force
and regain its original shape once the
force has been removed.electret A permanently electriÜed
substance or body that has opposite
charges at its extremities. Electrets
resemble permanent magnets in
many ways. An electret can be made
by cooling certain waxes in a strong
electricÜeld.
electrical double layerA model
of the interface between an electrode
and the solution close to it. In this
model a sheet of one type of elec-
trical charge surrounds the surface
of the electrode and a sheet of
the opposite charge surrounds the193 electrical double layer
e