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

The resistance of the bulb filament is $100 \ \Omega$ at a temperature of $100^{\circ} C$. If its temperature coefficient of resistance is $0.005 \ ^{\circ} C^{-1}$,at what temperature will its resistance become $200 \ \Omega$ (in $^{\circ} C$)?

The cross-sections of wires made of the same material and having the same length are shown in the figure. What can be said about their resistances?

For which of the following does the resistance decrease upon increasing the temperature?

As the temperature increases,the electrical resistance:

Two conductors have the same resistances at $0^{\circ} C$ but their temperature coefficients of resistance are $\alpha_1$ and $\alpha_2$. The respective temperature coefficients for their series and parallel combinations are :