DC conductivity and AC conductivity

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AC conductivity
There is another method to measure conductivity by using alternating voltage , voltage changes with frequency , i.e ac voltage , so it is called ac conductivity. A.c. conductivity is one of the studies done on solids in order to characterize the bulk resistance of the crystalline sample. The measurement of a.c conductivity is based on the measurement of sample impedance over a range of temperatures and frequencies where by plotting impedance versus frequency we can derive information about the electrical properties of the sample. Researches found that the ac conductivity is proportional to frequency through the following relation:-

σAc (ω,T) = A ωs ………. (5)

Where σAc is the ac conductivity , A is constant, ω is the angular frequency = 2πf, s is the exponent of the frequency component , where s>=1, and T is the temperature.