Wires $P$ and $Q$ have the same resistance at ordinary (room) temperature. When heated,the resistance of $P$ increases and that of $Q$ decreases. We conclude that:

Copper and silicon are cooled from $300 \ K$ to $60 \ K$. The specific resistance:

For wiring in the home,one uses $Cu$ wires or $Al$ wires. What considerations are involved in this?

$A$ metal rod of length $10 \text{ cm}$ and a rectangular cross-section of $1 \text{ cm} \times 0.5 \text{ cm}$ is connected to a battery across opposite faces. The resistance will be

$A$ silver wire has a resistance of $2.1\; \Omega$ at $27.5^{\circ} C$ and a resistance of $2.7\; \Omega$ at $100^{\circ} C$. Determine the temperature coefficient of resistivity of silver.

This question contains statement-$1$ and statement-$2$. Of the four choices given after the statements,choose the one that best describes the two statements.
statement-$1$: The temperature dependence of resistance is usually given as $R=R_{0}(1+\alpha \Delta t)$. The resistance of a wire changes from $100 \; \Omega$ to $150 \; \Omega$ when its temperature is increased from $27^{\circ} C$ to $227^{\circ} C$. This implies that $\alpha=2.5 \times 10^{-3} /^{\circ} C$.
statement-$2$: $R=R_{0}(1+\alpha \Delta t)$ is valid only when the change in the temperature $\Delta t$ is small and $\Delta R=(R-R_{0}) << R_{0}$.