  The impedance boundary condition is used to calculate the Casimir force in
configurations of two parallel plates and a shpere (spherical lens) above a
plate at both zero and nonzero temperature. The impedance approach allows one
to find the Casimir force between the realistic test bodies regardless of the
electromagnetic fluctuations inside the media. Although this approach is an
approximate one, it has wider areas of application than the Lifshitz theory of
the Casimir force. The general formulas of the impedance approach to the theory
of the Casimir force are given and the formal substitution is found for
connecting it with the Lifshitz formula. The range of micrometer separations
between the test bodies which is interesting from the experimental point of
view is investigated in detail. It is shown that at zero temperature the
results obtained on the basis of the surface impedance method are in agreement
with those obtained in framework of the Lifshitz theory within a fraction of a
percent. The temperature correction to the Casimir force from the impedance
method coincides with that from the Lifshitz theory up to four significant
figures. The case of millimeter separations which corresponds to the normal
skin effect is also considered. At zero temperature the obtained results have
good agreement with the Lifshitz theory. At nonzero temperature the impedance
approach is not subject to the interpretation problems peculiar to the
zero-frequency term of the Lifshitz formula in dissipative media.
