If a wire of resistance $R$ is melted and recasted to half of its length,then the new resistance of the wire will be

The length of a metallic wire is increased by $20 \%$ and its area of cross-section is reduced by $4 \%$. The percentage change in resistance of the metallic wire is $.......$ (in $\%$)

The resistance of a conductor at $15^{\circ}C$ is $16\, \Omega$ and at $100^{\circ}C$ is $20\, \Omega$. What will be the temperature coefficient of resistance of the conductor?

As shown in the schematic below,a rod of uniform cross-sectional area $A$ and length $l$ is carrying a constant current $i$ through it and the voltage across the rod is measured using an ideal voltmeter. The rod is stretched by the application of a force $F$. Which of the following graphs would show the variation in the voltage across the rod as a function of the strain $\varepsilon$ when the strain is small? Neglect Joule heating.

The resistivity of a wire depends on its

$A$ conducting wire has length $L_1$ and diameter $d_1$. After stretching,the same wire's length becomes $L_2$ and diameter $d_2$. The ratio of resistance before and after stretching is: