$A$ wire of resistance $160\,\Omega$ is melted and drawn into a wire of one-fourth of its original length. The new resistance of the wire will be $......\Omega$.

Which of the following has a negative temperature coefficient?

At room temperature $(27^\circ \text{C})$ the resistance of a heating element is $100 \ \Omega$. What is the temperature of the element if the resistance is found to be $137 \ \Omega$,given that the temperature coefficient of the material of the resistor is $1.35 \times 10^{-4} \ ^\circ \text{C}^{-1}$ (in $^\circ \text{C}$)?

Describe the effect of temperature on the electrical resistance of metals and semiconductors.

Explain how the resistance of a conductor depends on its dimensions.

$A$ wire of resistance $R_{1}$ is drawn out so that its length is increased by twice of its original length. The ratio of the new resistance to the original resistance is: