very high temperature the distribution becomes very disffuse and spread out. As this occurs the fermi energy moves downward very slowly at first then more rapidly when E=Ef f(E) has the more downward very slowly 1/2 which allows its position to be clearly observed in figure. Q.NO.17 Find range of energy over which the probability of occupation of a quantum state of a system obey fermi-Dirac statics drops from 0.9 to 0.1 . What does this answer became if the occupation limits are 0.99 to 0.01? The fermi distribution proper as given by f(\varepsilon)=\frac{1}{\left.1+e^{c \varepsilon-\varepsilon_{f}}\right) \mid k r} At temperature T=0 this function is seem to become a step function of the form f(E)=0.9 E=0.9 Ef=0.1 (E>Ef)=0 As the temperature increases the edges of step function become slightly rounded and function spreads out varying.

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