Describe the nature of the $V-I$ graph for a nichrome wire. ($V =$ Potential difference,$I =$ Current)
$A$ metallic wire of $625 \, mm$ length offers a $4 \, \Omega$ resistance. If the resistivity of the metal is $4.8 \times 10^{-7} \, \Omega \cdot m$,calculate the cross-sectional area of the wire.

(N/A) The $V-I$ graph for a nichrome wire is a straight line passing through the origin,as nichrome follows Ohm's law.
Given:
Resistivity $\rho = 4.8 \times 10^{-7} \, \Omega \cdot m$
Length $L = 625 \, mm = 0.625 \, m$
Resistance $R = 4 \, \Omega$
Using the formula for resistance: $R = \frac{\rho L}{A}$
Rearranging for area $A$: $A = \frac{\rho L}{R}$
Substituting the values:
$A = \frac{4.8 \times 10^{-7} \times 0.625}{4}$
$A = 1.2 \times 10^{-7} \times 0.625$
$A = 0.75 \times 10^{-7} \, m^2$ or $7.5 \times 10^{-8} \, m^2$