If a copper wire is stretched to increase its length by $20 \% $,the percentage increase in resistance of the wire 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:

The $I-V$ graph for a conductor at two different temperatures $100^{\circ} C$ and $400^{\circ} C$ is as shown in the figure. The temperature coefficient of resistance of the conductor is about (in per degree Celsius).

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

$A$ wire of resistance $R_{1}$ is drawn out so that its length is increased by twice of its original length. The ratio of the new resistance to the original resistance is:

The resistance of a tungsten wire at $150^{\circ} C$ is $133 \Omega$. The temperature coefficient of resistance is $0.0045^{\circ} C^{-1}$. The resistance of this wire at $500^{\circ} C$ is: (in $\Omega$)