If the resistance of a conductor is $5\,\Omega$ at $50\,^{\circ}\text{C}$ and $7\,\Omega$ at $100\,^{\circ}\text{C}$,then the mean temperature coefficient of resistance of the material is ............... $^{\circ}\text{C}^{-1}$.

If the ratio of the masses of wires of the same material is $1 : 3 : 5$ and the ratio of their lengths is $5 : 3 : 1$,what is the ratio of their resistances?

The specific resistance (resistivity) of material $B$ is twice that of material $A$. Two wires are prepared from these materials having the same resistance. If the diameter of wire $B$ is twice the diameter of wire $A$,then the ratio of the lengths of the two wires $l_B / l_A$ is equal to ......

$A$ cylindrical wire $P$ has resistance $10 \ \Omega$. $A$ second wire $Q$ has length and diameter half that of $P$. If the material of both the wires is same,then the resistance of wire $Q$ is (in $\Omega$)

$A$ given piece of wire of length $l$ and radius $r$ and resistance $R$ is stretched uniformly to a wire of radius $\frac{r}{2}$. Its new resistance is .................. $R$.

The variation of the resistance of a conductor with temperature is as shown in the graph. The temperature coefficient $(\alpha)$ of the conductor is: