Which of the following gives the correct expression for potential gradient in terms of the resistivity $(\rho)$ of the wire?
Answer & explanation
Correct answer: option 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 $ρIA^{-1}$