The resistances of a wire at temperatures $t\,^oC$ and $0\,^oC$ are related by:

$A$ resistance $R$ is stretched to four times its length. Its new resistance will be

The resistivity of iron is $1 \times 10^{-7} \, \Omega \cdot m$. The resistance of an iron wire of a particular length and thickness is $1 \, \Omega$. If the length and the diameter of the wire are both doubled, then the resistivity in $\Omega \cdot m$ will be:

The resistance of an incandescent lamp is

At room temperature $(27.0^{\circ} C)$,the resistance of a heating element is $100\; \Omega$. What is the temperature (in $^{\circ} C$) of the element if the resistance is found to be $117\; \Omega$,given that the temperature coefficient of the material of the resistor is $1.70 \times 10^{-4}\; ^{\circ} C^{-1}$?

$A$ cell of $emf$ $E$ and internal resistance $r$ is connected across an external resistance $R$. Plot a graph showing the variation of potential difference $(V)$ across $R$ versus $R$.