$A$ conducting wire has length $L_1$ and diameter $d_1$. After stretching,the same wire's length becomes $L_2$ and diameter $d_2$. The ratio of resistance before and after stretching is:

Two square-shaped metal plates $A$ and $B$ of the same thickness $(t)$ and of the same material are connected as shown in the figure. The side of $B$ is twice that of $A$. If the resistances of $A$ and $B$ are $R_A$ and $R_B$ respectively, then $\frac{R_A}{R_B}$ is:

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 ............... $^{\circ}\text{C}^{-1}$.

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

Two metal wires of identical dimensions are connected in series. If $\sigma_1$ and $\sigma_2$ are the conductivities of the metal wires respectively,the effective conductivity of the combination is

Two wires are made of the same material. The length and diameter of the second wire are both double those of the first wire. What will be the resistance of the first wire compared to the second wire?