  The electrical laws and Carnot cycle of Isolated Horizon (IH) are
investigated in this paper. We establish the Ohm's law and Joule's law of an
Isolated Horizon, and find that the conceptual picture of black holes (Membrane
Paradigm) can also apply to this kind of quasi-local black holes. We also
investigate the geometrical properties near a non-rotating IH, and find that
under the first-order approximation of r, there exist a Killing vector and a
Hamiltonian conjugate to it, so this vector is a physical observer. We
calculate the energy as measured at infinity of a particle at rest outside a
non-rotating IH, and use this result to construct a reversible Carnot cycle
with the Isolated Horizon as a cold reservoir, which confirms the thermodynamic
nature of Isolated Horizon.
