The temperature coefficient of resistance at $0\,^{\circ}\text{C}$ is $\alpha = 0.00125\,^{\circ}\text{C}^{-1}$. At a temperature of $25\,^{\circ}\text{C}$,the resistance of a conductor is $1\,\Omega$. Find the temperature at which the resistance becomes $1.2\,\Omega$.

The conductivity of a superconductor is

$A$ heating element using nichrome connected to a $230 \;V$ supply draws an initial current of $3.2 \;A$ which settles after a few seconds to a steady value of $2.8 \;A$. What is the steady temperature of the heating element if the room temperature is $27.0^{\circ} C$ (in $^{\circ} C$)? The temperature coefficient of resistance of nichrome averaged over the temperature range involved is $1.70 \times 10^{-4} \;^{\circ} C^{-1}$.

Explain the qualitative dependence of resistivity on temperature.

$A$ material '$B$' has twice the specific resistance of '$A$'. $A$ circular wire made of '$B$' has twice the diameter of a wire made of '$A$'. Then,for the two wires to have the same resistance,the ratio $\frac{l_B}{l_A}$ of their respective lengths must be

Two wires of the same material have lengths $L$ and $2L$ and cross-sectional areas $4A$ and $A$ respectively. The ratio of their specific resistance would be