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Explain the terms like electrical resistance and resistivity of a conductor

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  • The resistance is known as the property of substance by virtue of which it opposes the flow of current through it.

  • Formula-

For a conductor of resistivity \rho having a length of a conductor= l

and  Area of a crosssection of conductor= A

Then the resistance of a conductor is given as 

          R=\rho \frac{l}{A}

Where \rho\rightarrow Resistivity

  • Its S.I unit is  Volt/Amp or ohm (\Omega)

  • Its Dimensions is  ML^{2}T^{-3}A^{-2}

 Resistivity or Specific Resistance (\rho)

  • As R=\rho \frac{l}{A}

If l=1 m and A= 1 m^2

Then R=\rho

So Resistivity is numerically equal to the resistance of a substance having a unit area of cross-section and unit length.

  • If m is the mass, n is the number of electrons per unit volume, e is the charge of the electron and \tau is the relaxation time


  •        Its S.I Unit is  Ohm.m 

  • Its Dimensions-ML^{3}T^{-3}A^{-2}

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