  We have considered the response at two energies corresponding to two plateaus
in the quantum Hall effect. Since the thermoelectric power involves the
derivative of conductivity with respect to energy, we introduce the concept of
a line width and hence an activation energy. We then use the Hall conductivity
to define the thermoelectric power at the centre of two plateaus, which is
found to vary monotonically as T^2 at low temperatures with fixed magnetic
field. At elivated temperatures, the thermoelectric power varies as
T(exp-\Delta/k_BT).
