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Which of the following gives the correct expression for potential gradient in terms of the resistivity $(\rho)$ of the wire? |
$k=I \rho A^{-1}$ $k=I \rho l A^{-1}$ $k=\frac{I \rho}{lA}$ $k=I A \rho$ |
$k=I \rho A^{-1}$ |
The correct answer is Option (1) → $k=I \rho A^{-1}$ The resistance of a given wire - $R=ρ\frac{L}{A}$ $V=IR$ [By ohm's law] $V=Iρ\frac{L}{A}$ $⇒\frac{V}{L}=\frac{I}{A}$ ∴ Potential gradient is $ρIA^{-1}$ |
