1. Tardigrade
  2. Question
  3. Physics
  4. A cylindrical metal wire of length l and cross-sectional area S, has resistance R, conductance G, conductivity σ and resistivity ρ . Which one of the following expression for σ is valid?

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Q. A cylindrical metal wire of length $ l $ and cross-sectional area S, has resistance R, conductance G, conductivity $ \sigma $ and resistivity $ \rho $ . Which one of the following expression for $ \sigma $ is valid?

CMC MedicalCMC Medical 2012

Solution:

We know that, conductivity $ \sigma =\frac{1}{\rho } $ ?(i) and conductance, $ G=\frac{1}{R} $ ...(ii) $ \Rightarrow $ $ GR=1 $ From Eqs. (i) and (ii), we get $ \sigma =\frac{GR}{\rho } $