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Define 'relaxation time'. Derive the expressionfor electrical conductivity of a material in terms of relaxation time. |
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Answer» SOLUTION :The average time between two successive collisions of free electrons is known as relaxation time. We know that drift velocity `V_d=(eEtau)/m` We have `I=heAV_d` …(1) SUBSTITUTE for `V_d` in equation (1) and we get `I=("ne"AeEtau)/m=("ne"^2AEtau)/m rArr I/A=("ne"^2Etau)/m` `J=("ne"^2Etau)/m ""because j=I/A` We know that `j=sigma E` `therefore sigma cancelE=("ne"^2 cancelE tau)/m` `sigma=("ne"^2TAU)/m`. |
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